• Information Systems Review
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• v.14 no.1
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• pp.1-19
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• 2012

A large-scale IS development project takes a long time, thus its project manager needs to be more careful on risk management. In particular, appropriate cutover decision making is critical in large-scale IS development projects because the opening of the large-scale IS significantly impacts the organization. Regardless of its importance, cutover decision making in conventional IS development projects has been done in a quite simple way. Conventional cutover decisions have been made by considering just whether the new IS operates or not from the system, application, and data implementation perspectives. However, this approach may lead to unsatisfactory performance or system failure in complex large-scale IS development. Under this background, we propose a new framework for cutover decision making on large-scale IS projects. To validate the applicability, we applied the framework to a core banking system development case. The case study shows that our framework is effective in proper cutover decision making.

• KDI Journal of Economic Policy
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• v.14 no.1
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• pp.121-145
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• 1992

This paper examines characteristics of time series data related to the construction investment(stationarity and time series components such as secular trend, cyclical fluctuation, seasonal variation, and random change) and surveys predictibility, fitness, and explicability of independent variables of various models to build a short-term construction investment forecasting model suitable for current economic circumstances. Unit root test, autocorrelation coefficient and spectral density function analysis show that related time series data do not have unit roots, fluctuate cyclically, and are largely explicated by lagged variables. Moreover it is very important for the short-term construction investment forecasting to grasp time lag relation between construction investment series and leading indicators such as building construction permits and value of construction orders received. In chapter 3, we explicate 7 forecasting models; Univariate time series model (ARIMA and multiplicative linear trend model), multivariate time series model using leading indicators (1st order autoregressive model, vector autoregressive model and error correction model) and multivariate time series model using National Accounts data (simple reduced form model disconnected from simultaneous macroeconomic model and VAR model). These models are examined by 4 statistical tools that are average absolute error, root mean square error, adjusted coefficient of determination, and Durbin-Watson statistic. This analysis proves two facts. First, multivariate models are more suitable than univariate models in the point that forecasting error of multivariate models tend to decrease in contrast to the case of latter. Second, VAR model is superior than any other multivariate models; average absolute prediction error and root mean square error of VAR model are quitely low and adjusted coefficient of determination is higher. This conclusion is reasonable when we consider current construction investment has sustained overheating growth more than secular trend.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.161-169
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• 2011

Focal mechanism solutions in the central and western areas of the Korean Peninsula (36-37.8$^{\circ}N$, 126-128$^{\circ}E$) were obtained from the analysis of the recent seventeen earthquakes (M${\geq}$2.2) which occurred from January, 2005 to May, 2010. The spatial differences between the epicenters recalculated by this study and those announced by the Korea Meteorological Administration are less than $0.03^{\circ}$, indicating a small deviation. Focal mechanism solutions were obtained from the analysis of P wave polarities, SH wave polarities and SH/P amplitude ratios. The focal mechanism solutions show dominant strike-slip faulting or oblique slip faulting with strike-slip components. The P-axes trends are mainly ENE-WSW or E-W directions. The direction of fault plane and auxillary fault plane with NNE-SSW and WNW-ESE are almost parallel to the general trends of lineaments in the study area. The results also show that focal mechanism solutions and the main axis of stress field in the Kyonggi massif and Okchon belt are almost same.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1143-1156
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• 2012

One of the important purposes of most water resources systems is to prevent from drought damages. However, there are uncertainties in water supply plans from a reservoir due to factors such as limitation of available data, inaccuracy of surveyed data, unsuitability of analysis method, and climate change. In actual operating process, severe drought exceeding the water supply capability makes the normal water usage difficult. In Korea, however, alternative water source such as a development of new water project is very limited in case of water shortages due to drought. Especially, since there is no standard to evaluate the water supply effect considering severe drought damages, it is difficult to prepare the practical measures. In this study, water shortage events of existing multipurpose reservoirs are analyzed and the method of using low-storage emergency water supply is studied by using Water Shortage Index (WSI). The water shortage events are analyzed and the effect of water shortage decrease is evaluated using the existing inflow data of multi-purpose reservoirs. The results show that Imha, Daechung, Hapchon and Namkang reservoirs are highly vulnerable to the severe drought and required to develop additional emergency water source.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.435-445
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• 2017

This study was conducted to overcome the limitations of prior research on the equity of medical care performed by identifying simple differences in the use of medical care or using limited medical needs and medical utilization indicators. Specifically, we used activity limits, chronic diseases, and subjective health status as medical needs, and used outpatient, inpatient, and emergency services as medical uses. In addition, we used concentration index, concentration curve, and Le Grand factor to analyze the equity of medical use considering medical needs. The main results are as follows. First, the amount of medical care for the low-income class is higher than that of the high-income class when considering the concentration of medical use. In particular, the number of hospitalization days for low-income households and hospitalization fees were higher than the fees of outpatient medical consultation and emergency room usage. Second, medical needs were concentrated in the low income class. In other words, low-income group is not as healthy as the high-income group. Third, the Le Grand factor was calculated in order to confirm the fairness of the medical uses considering the medical needs. Even if medical needs are taken into consideration, the high-income earners will have a large amount of medical care. In addition, when considering the limitation of activity and the number of chronic diseases, the medical use of the high income class was more frequent. However, when the subjective health condition and the chronic illness were considered, medical use of the low income class was more frequent. This may be due to the underestimation of the medical needs of the low-income earners by neglecting their own health status and perception of chronic diseases.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.127-145
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• 1998

Unlike water or air quality standards that have been established by legislation using potential human health impact as the primary criterion, soil quality depends on the soils primary function and its relevant environmental factors, which is much more site- and soil specific. A properly characterized soil quality assessment system should serve as an indicator of the soil capacity to produce safe and nutritious food, to enhance human and animal health, and to overcome degrative processes. For our proposed example, a high quality soil with regard to maintaining an adequate soil productivity as a food production resources must accommodate soil and water properties, food chain, sustainability and utilization, environment, and profitability, that (i) facilitate water transfer and absorption, (ii) sustain plant growth, (iii) resist physical degradation of soil, (iv) produce a safe food resources, (v) cost-effective agricultural management. Possible soil quality indicators are identified at several levels within the framework for each of these functions. Each indicator is assigned a priority or weight that reflects its relative importance using a multi-objective approach based on principles of systems to be considered. To do this, individual scoring system is differentiated by the several levels from low to very high category or point scoring ranging from 0 to 10, And then weights are multiplied and products are summed to provide an overall soil quality rating based on several physical and chemical indicators. Tlne framework and procedure in developing the soil quality assessment are determined by using information collected from an alternative and conventional farm practices in the regions. The use of an expanded framework for assessing effects of other processes, management practices, or policy issues on soil quality is also considered. To develop one possible form for a soil quality index, we should permit coupling the soil characteristics with assessment system based on soil properties and incoming and resident chemicals. The purpose of this paper is to discuss approaches to defining and assessing soil quality and to suggest the factors to be considered.

• Journal of Preventive Medicine and Public Health
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• v.24 no.1 s.33
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• pp.57-69
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• 1991

This study examined the cross-sectional association of central body fat distribution with hypertension as well as the superiority of medial calf skinfold measured as peripheral fat distribution over the conventional triceps skinfold using 450 Korean Navy divers selected by authors' convenience in 1990. Their mean age was 27.9 and range of it was 19-51. The centrally located body fat was approximated by subscapular skinfold and peripherally located fat by triceps and medial calf skinfolds. Four indices were constructed from these skinfold measures to reflect central versus peripheral fat distribution pattern : 2 ratios and 2 differences. After controlling age and overall obesity (body mass index), prevalance odds ratios of the 2/4, 3/4, 4/4 quartiles of subscapular skinfold comparing with lowest 1/4 quartile were 2.05(95% confidence interval, CI 1.18-3.59), 2.02(95% CI 1.06-3.86), 4.00 (95% CI 1.99-8.06) respectively. The difference of subscapular and medial calf skinfolds was associated with hypertension (odds ratio 2.45, 95% CI 1.28-4.68 comparing highest with lowest quartiles). Triceps and medial calf skinfolds alone did not show any odds ratio not including unity. The adjusted odds ratios were generally reduced in small magnitude compared with crude odds ratios not adjusted for age and overall obesity. The medial calf skinfold appeared to be more representative of peripheral body fat distribution than triceps skinfold. These findings suggest that central fat distribution rather than peripheral distribution is associated with hypertension independent of age and overall level of obesity and medial calf skinfold may replace conventional triceps skinfold in predicting peripheral distribution of body fat.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.613-622
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• 2009

The modal spilt of highway has been increased and the one of railway has been decreased from 17.2%(1990) to 6.3%(2006). In this context, it is meaningful to examine the competitiveness of the railroad of Korea. The objective of this study is to analyze the competitiveness of railroad with the highway so that countermeasures improving the competitiveness of railroad could be suggested. For this, firs of all, indicators representing the competitiveness of the railroad transport are determined. The main influencing factors for mode choice include transport time, transport cost and level of service. Three types of commodity, container, cement and steel are the target for the analysis. It was found that the overall competitiveness of railroad transport is weaker compared with highway even for the main freight origin-destination pairs. It means that the freight transport system is focused on road rather than railroad. Therefore, we need to remeasure the competitiveness of railroad transport related to methods for freight railroad competitiveness improvement.

• Science of Emotion and Sensibility
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• v.17 no.3
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• pp.95-106
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• 2014

This research analyzed biosignals associated with the change of emotion from lighting felt by the occupants and task type under various indoor thermal environments and illuminance, and examined the biosignals' impacts on work. To this end, the indoor thermal environment was constructed on the basis of PMV (predicted mean vote) index value, and various indoor environments were created by changing the brightness of LED stands. In this manner, a variety of indoor environments were constructed, and experiments were carried out. This research evaluates the sensibility response to lighting through a questionnaire survey in the given environment and incorporates different types of error searches. In this way, changes were analyzed by measuring electroencephalogram (EEG) and electrocardiograms (ECG). As a result, all biosignals on the task type showed significant differences from the thermal environment change. When PMV index value was 0.8 (temperature: $25^{\circ}C$, humidity: 50 %), concentration and attention were the most activated. However, the biosignals did not show significant differences from the illuminance change. Concentration on an occupant's work capability was confirmed to be closely related to the thermal environment. As for the subjective emotional response to lighting, the occupants felt comfort as illuminance was lower, while they felt discomfort as illuminance was higher. However, there were no significant differences from the thermal environment change.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.275-284
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• 2021

Survival analysis was used to analyze whether there is a difference in the effect of leverage on corporate failure according to the firm size. A total of 25,250 (year-company) companies listed on the Korea Stock Exchange and KOSDAQ market from 1999 to 2019 were analyzed. First, the increase in leverage generally acts as a factor that increases the possibility of corporate failure. On the other hand, the increase in the trade payable ratio lowered the possibility of failure of the company. The increase in corporate trade payable was perceived as a factor in reducing the possibility of corporate failure because it was considered the active development of business activities or active use of interest-free debt rather than leading to an increase in corporate risk. Second, a higher leverage ratio and trade payable ratio in large firms lowered the possibility of corporate failure. In the SMEs, all types of leverage increases are a factor that increases corporate failure. Overall, the effect of leverage on corporate failure differs according to the size of the company.