• The Korean Journal of Financial Management
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• v.23 no.2
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• pp.57-83
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• 2006

The purpose of this paper is to analyze the efficiency and productivity change and inefficiency cause of the korean non-life insurance companies of the before($1993{\sim}1996$) and after($1998{\sim}2004$) of IMF. we use DEA (Data Envelopment Analysis) model to measure company efficiency and MPI(Malmquist productivity indices) to measure company productivity change and Tobit regression to analyze inefficiency cause. we utilize ten non-life insurance companies in korea and the time-series data for eleven from 1993 to 2004 except 1997. The empirical results show the following findings. First, total cost efficiency shows that the after of IMF decrease of 3.7% over the before of IMF and MPI change indicates that the after of IMF increase 7.7% over the before IMF. Second, the results of Tobit regression to analysis the cause of inefficiency show that total cost efficiency is positively related invested assets, acquisition expenses ratio, collection expenses ratio and is negatively related solicitors ratio, personnel expenses ratio, land & buildings expenses ratio, loss ratio, net operating expenses ratio. Especially inefficiency of small-to-mid sized companies is main cause of total cost efficiency of non-life insurance companies in korea. Small-to-mid sized companies endeavored various aspects of business strategies.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.2
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• pp.243-250
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• 2003

Purpose : The purpose of this study was to suggest the number about the projected workforce of Certified Insurance Reviewer Nurses(CIRN) in Korea. Method : The following methods were used for this study: 1) national and international internet data were collected. 2) demand model was used for the prediction of the projected workforce of CIRN. 3) experts in insurance reviewing were contacted to get an opinion and information about the criteria of distribution and scope of CIRNs, 4) we figured out the maximum and minimum number of CIRN Korea needed as followed method, the maximum number was estimated that one CIRN would review 150 cases of Detailed Accounts for Examination and Treatment and the minimum was estimated 200 cases of it. 5) time series regression equation analysis was used for the prediction of number of CIRNs for the year 2003 to 2010. Result: 1) The prediction of CIRNs is as follows, there will be 2,313$\sim$2,827 of CIRN demanded in 2002, 2,500$\sim$3,069 in 2005 and 2,806$\sim$3,466 in 2010. 2) It is really desirable that CIRNs not only work for reviewing the detailed accounts for examination and treatment in hospital but also for inspecting allowance in individual insurance company. Conclusion : It is very desirable that the CIRN advocate the clients' rights because they will work for them satisfactory rather than other hospital experts group. But before settling the system of the CIRN in Korea, there would be its own professional role identity and a code of conduct.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.259-266
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• 2018

Objectives: Considered the "national fish" in Korea, the walleye pollock (Gadus chalcogrammus) has disappeared in the East Sea (Sea of Japan), a main habitat and fishing ground for the species. The reason for the disappearance is still a matter of controversy. This study was performed to investigate the long-term relationship between the walleye pollock catch and various meteorological and oceanographic factors in these waters. Methods: Fishery data on walleye pollock and data on meteorological and marine environmental factors over the 30 years (1981-2010) were obtained from the official national database. Time series analysis and correlation and regression analyses were performed to study the relationships. Results: Both air temperature and sea surface temperature in the East Sea rose over these 30 years, and the latter became more prominent. Salinity and dissolved oxygen showed a tendency to decrease while concentrations of nutrients such as nitrite nitrogen and nitrate nitrogen showed an increasing tendency. Sea surface temperature, air temperature, atmospheric pressure, and wind grade were negatively correlated with the catch size of walleye pollock (p<0.05), but salinity was positively correlated (p<0.001). Conclusion: The results of this study indicate that climate change, especially ocean warming, affected the habitat of walleye pollock. The results also indicate that lower sea surface and air temperatures, milder wind grade, and higher salinity were preferred for the survival of the fish species. It is necessary to pay attention to changes of the ocean ecosystem in terms of environmental pollution as well as seawater temperature.

• Geophysics and Geophysical Exploration
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• v.17 no.3
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• pp.121-128
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• 2014

As the permeability is an important parameter to characterize the ease with which a porous medium transmits fluids, it is usually obtained by fluid flow experiment using core samples. In order to measure the permeability, however, an experimental apparatus is required and it might take long measurement time, especially for tight samples. In this study, the relationship between permeability and porosity as well as drying rate has been investigated to predict the permeability without a series of measuring experiments. Porosity is measured by drying monitoring method, which measures weight variation continuously while drying surface-dried saturated sample, and drying rate is obtained from weight variation ratio with respect to the water saturation. The total of 6 Berea sandstone samples, which have a permeability range of 70 to 670 mD, were used in this work, and a new and empirical equation which could predict permeability of porous sandstone by using porosity and drying rate were obtained through regression analysis.

• Radiation Oncology Journal
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• v.32 no.3
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• pp.179-186
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• 2014

Purpose: To study the long-term outcomes and tolerance in our patients who received dose escalated radiotherapy in the early salvage post-prostatectomy setting. Materials and Methods: The medical records of 54 consecutive patients who underwent radical prostatectomy subsequently followed by salvage radiation therapy (SRT) to the prostate bed between 2003-2010 were analyzed. Patients included were required to have a pre-radiation prostate specific antigen level (PSA) of 2 ng/mL or less. The median SRT dose was 70.2 Gy. Biochemical failure after salvage radiation was defined as a PSA level >0.2 ng/mL. Biochemical control and survival endpoints were analyzed using the Kaplan-Meier method. Univariate and multivariate Cox regression analysis were used to identify the potential impact of confounding factors on outcomes. Results: The median pre-SRT PSA was 0.45 ng/mL and the median follow-up time was 71 months. The 4- and 7-year actuarial biochemical control rates were 75.7% and 63.2%, respectively. The actuarial 4- and 7-year distant metastasis-free survival was 93.7% and 87.0%, respectively, and the actuarial 7-year prostate cancer specific survival was 94.9%. Grade 3 late genitourinary toxicity developed in 14 patients (25.9%), while grade 4 late genitourinary toxicity developed in 2 patients (3.7%). Grade 3 late gastrointestinal toxicity developed in 1 patient (1.9%), and grade 4 late gastrointestinal toxicity developed in 1 patient (1.9%). Conclusion: In this series with long-term follow-up, early SRT provided outcomes and toxicity profiles similar to those reported from the three major randomized trials studying adjuvant radiation therapy.

• Journal of Korean Neurosurgical Society
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• v.50 no.3
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• pp.231-234
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• 2011

Objective : Infection and bone resorption are major complications of cranioplasty and have been well recognized. However, there are few clinical series describing the epidural fluid collection (EFC) as complication of cranioplasty. This study was planned to identify the predictive factors and fate of EFC after cranioplasty. Methods : We reviewed retrospectively the demographic, clinical, and radiographic data in 59 patients who underwent a first cranioplsty following decompressive craniectomy during a period of 6 years, from January 2004 to December 2009. We compared demographic, clinical, and radiographic factors between EFC group and no EFC group. The predictive factors associated with the development of EFC were assessed by logistic regression analysis. Results : Overall, 22 of 59 patients (37.3%) suffered from EFC following cranioplasty. EFC had disappeared (n=6, 31.8%) or regressed (n=6, 31.8%) over time on follow up brain computed tomographic (CT) scans. However, 5 patients (22.7%) required reoperation due to symptomatic and persistent EFC. Predictive factors for EFC were male [odds ratio (OR), 5.48; 95% CI, 1.26-23.79], air bubbles in the epidural space (OR, 12.52; 95% CI, 2.26-69.28), and dural calcification on postoperative brain CT scan (OR, 4.21; 95% CI, 1.12-15.84). Conclusion : The most of EFCs could be treated by conservative therapy. Air bubble in the epidural space and dural calcification are proposed to be the predictive factors in the formation of EFC after cranioplasty.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7991-7995
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• 2015

Background: To identify the epidemiological characteristics of colorectal cancer mortality in China during the period of 1991-2011, and forecast the future five-year trend. Materials and Methods: Mortality data for colorectal cancer in China from 1991 to 2011 was used to describe epidemiological characteristics in terms of age group, gender, and rural/urban residence. Trend surface analysis was performed to analyze the geographical distribution of colorectal cancer. Four models including curve estimation, time series modeling, gray modeling and joinpoint regression were applied to forecast the trends for the future five years. Results: Since 1991 the colorectal cancer mortality rate increased yearly, and our results showed that the trend would continue to increase in the ensuing 5 years. The mortality rate in males was higher than that of females and the rate in urban areas was higher than in rural areas. The mortality rate was relatively low for individuals less than 60 years of age, but increased dramatically afterwards. People living in the northeastern China provinces or in eastern China had a higher mortality rate for colorectal cancer than those living in middle or western China provinces. Conclusions: The steadily increasing mortality of colorectal cancer in China will become a substantial public health burden in the foreseeable future. For this increasing trend to be controlled, further efforts should concentrate on educating the general public to increase prevention and early detection by screening. More effective prevention and management strategies are needed in higher mortality areas (Eastern parts of China) and high-risk populations (60+ years old).

• Environmental and Resource Economics Review
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• v.20 no.1
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• pp.99-118
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• 2011

'Low Carbon, Green Growth' may be the achievable target in industry section, depending on whether less reliance on fossil-fuels use can bring higher productivity growth in the long run. This paper tests for the short-run and long-run effects of investment on energy-saving equipments on productivity growth in the Korean manufacturing industries. The investment in energy efficiency causes an increase in costs (measurement effect) in the short-run, but in the long-run likely improve energy intensity and reduce costs (positive real effect) despite the delay in new other investment for technical innovation (negative real effect). A 2SLS regression was attempted to deal with endogeneity of energy-saving investment. The productivity effects were tested for five manufacturing sub-industries showing relatively high energy intensity with annual time series data from 1982 through 2006. No productivity effects were accepted for all five sub-industries except Chemical products. Positive real effect was considered to be exceeded by negative real effect, resulting in decreased productivity growth for Chemical products.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.141-154
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• 2018

In order to meet the ever-increasing demand for international air travel, several plans are underway to open new airports and expand existing provincial airports. However, existing air demand forecasts have been based on the total air demand in Korea or the air demand among major cities. There is not much forecast of regional air demand considering local characteristics. In this study, the outbound air travel demand in the southeastern region of Korea was analyzed and the fixed-effects model using panel data was proposed as an optimal model that can reflect the inherent characteristics of metropolitan areas which are difficult to observe in reality. The results of model validation show that panel data analysis effectively addresses the spurious regression and unobserved heterogeneity that are difficult to handle in a model using only a few macroeconomic indicators with time series characteristics. Various statistical validation and conformance tests suggest that the fixed-effects model proposed in this study is superior to other econometric models in predicting demand for international demand in the southeastern region.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.8
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• pp.561-570
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• 2004

In this paper, new architectures and comprehensive design methodologies of Genetic Algorithms(GAs) based Genetically optimized Neurofuzzy Networks(GoNFN) are introduced, and a series of numeric experiments are carried out. The proposed GoNFN is based on the rule-based Neurofuzzy Networks(NFN) with the extended structure of the premise and the consequence parts of fuzzy rules being formed within the networks. The premise part of the fuzzy rules are designed by using space partitioning in terms of fuzzy sets defined in individual variables. In the consequence part of the fuzzy rules, three different forms of the regression polynomials such as constant, linear and quadratic are taken into consideration. The structure and parameters of the proposed GoNFN are optimized by GAs. GAs being a global optimization technique determines optimal parameters in a vast search space. But it cannot effectively avoid a large amount of time-consuming iteration because GAs finds optimal parameters by using a given space. To alleviate the problems, the dynamic search-based GAs is introduced to lead to rapidly optimal convergence over a limited region or a boundary condition. In a nutshell, the objective of this study is to develop a general design methodology o GAs-based GoNFN modeling, come up a logic-based structure of such model and propose a comprehensive evolutionary development environment in which the optimization of the model can be efficiently carried out both at the structural as well as parametric level for overall optimization by utilizing the separate or consecutive tuning technology. To evaluate the performance of the proposed GoNFN, the models are experimented with the use of several representative numerical examples.