• Journal of Korea Water Resources Association
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• v.50 no.3
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• pp.191-200
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• 2017

A robust parameter set (ROPS) selection framework for an unsteady flow model was developed by combining Pareto optimums obtained by outcomes of model calibration using multi-site observations with the minimax regret approach (MRA). The multi-site calibration problem which is a multi-objective problem was solved by using an aggregation approach which aggregates the weighted criteria related to different sites into one measure, and then performs a large number of individual optimization runs with different weight combinations to obtain Pareto solutions. Roughness parameter structure which can describe the variation of Manning's n with discharges and sub-reaches was proposed and the related coefficients were optimized as model parameters. By applying the MRA which is a decision criterion, the Pareto solutions were ranked based on the obtained regrets related to each Pareto solution, and the top-rated one due to the lowest aggregated regrets of both calibration and validation was determined as the only ROPS. It was found that the determination of variable roughness and the corresponding standardized RMSEs at the two gauging stations varies considerably depending on the combinations of weights on the two sites. This method can provide the robust parameter set for the multi-site calibration problems in hydrologic and hydraulic models.

• Journal of Korea Water Resources Association
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• v.38 no.6 s.155
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• pp.495-504
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• 2005

The objective of this study is to estimate the impacts of land cover change on the runoff behavior using Hydrologic Simulation Program-Fortran (HSPF) model and Landsat images. Land cover maps were prepared using three every ten years from 1980 to 2000 of the upper watershed ($258\;km^2$) of Gyeongan stream. Hydrologic parameters of HSPF were calibrated using observed data (1999 - 2000) and validated using observed data (2001, 2003) at Gyeongan gauge station. The simulation results showed that runoff volume and peak rate increased as $15.0\;km^2$ forest areas decreased and $19.3\;km^2$ urban areas increased for 20 years land use changes. The runoff volume showed a higher rate of increase in wet year (2003, 1709.4 mm) than in dry year (2001, 871.2 mm). The peak runoff increased $13.3\;\%$ in normal year (2000, 1257.3 mm) because the year has the highest rain intensity (241.3 mm/hr) among the test years. The runoff volume of a dry season and a wet season (May - September) in normal year 2000 increased $4.4\;\%$ and decreased $8.1\;\%$, respectively.

• The Journal of Internal Korean Medicine
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• v.27 no.3
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• pp.639-652
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• 2006

Objective : The etiology of chronic prostatitis is likely multifactorial, resulting from either a cascade of events after an initiating factor or from a variety of etiologic mechanisms. There is substantiating evidence to support the role of the inflammatory responses in its pathogenesis, and the clinical value in the evaluation of therapeutic efficacy. Forsythiae Frucus has been traditionally used in treatment of inflammatory diseases, including of prostatitis and urinary tract inflammation. In this study, we investigated the effects of Forsythiae Frucus on inflammatory cytokines and cyto-pathological alternation in the rat model of chronic non-bacterial prostatitis induced by castration and $17{\beta}$-estradiol treatment. Methods : Two-month-old rats were treated with $17{\beta}$-estradiol after castration for induction of experimental non-bacterial prostatitis. which is similar to human chronic prostatitis in histopathological profiles. Forsythiae Frucus as an experimental specimen, and testosterone as a positive control, were administered orally. The prostates were evaluated by histopathologlcal parameters including the epithelial score and epithelio-stromal ratio for glandular damage. and the expression of inflammatory cytokine genes including interleukin (IL)-$1{\beta}$, IL-5, IL-12, tumor necrosis factor (TNF)-$\alpha$. eotaxin, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2(cox-2). Results : While prostates of control rats revealed severe acinar gland atrophy and stromal proliferation. the rats treated with Forsythiae Frucus showed a diminished range of tissue damage. Epithelial score was improved in the Forsythiae Frucus group over that of the control (P<0.05). The epithelia-stromal ratio was lower in the Forsythiae Frucus group when compared to that of the control (P<0.05). In the reverse transcription-polymerase chain reaction (RT-PCR) of inflammatory cytosine genes. Forsythiae Frucus inhibited the expression of IL-$1{\beta}$, TNF-$\alpha$, iNOS, cox-2 genes, while it modulated the expression of IL-5, which is an anti-inflammatory cytokine. Conclusions : These findings suggest that Forsythiae Frucus may protect the glandular epithelial cells and also inhibit stromal proliferation in association with the immune modulation including the suppression of inflammatory cytokines and increase of anti-inflammatory cytokines. From theses results. we suggest that Forsythiae Frucus could be a useful remedy agents for treating chronic non-bacterial prostatitis.

• The Journal of Internal Korean Medicine
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• v.27 no.3
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• pp.664-676
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• 2006

Objective : Although chronic non-bacterial prostatitis is a common disease, it is very difficult to treat effectively. Lygodium japonicum has been traditionally used in treatment of urinary tract inflammation and voiding disturbance. In this study, we investigated the therapeutic effects and action mechanism of Lygodium japonicum in the rat model of non-bacterial prostatitis induced by castration and testosterone treatment. Methods : Five-month-old rats were treated with 17$\beta$-estradiol after castration for induction of experimental non-bacterial prostatitis, which is similar to human chronic prostatitis in histopathological profiles. Lygodium japonicum and testosterone were administered as an experimental specimen and a positive control. respectively. The prostates were evaluated by histopathological parameters including the epithelial score and epithelio-stromal ratio for glandular damage. PCNA labeling index for cyto-proliferation and a TUNEL(deoxyuridine triphosphate biotin nick end-labeling) assay for cell apoptosis. Results : While prostates of control rats revealed severe acinar gland atrophy and stromal proliferation, the rats treated with Lygodium japonicum showed a diminished range of tissue damage. Epithelial score was improved in the Lygodium japonicum group over that of the control (P<0.05). The epithelio-stromal ratio was lower in the Lygodiutn japonicum group when compared to that of the control (P<0.05). Although there was no difference in PCNA and TUNEL positive cells of the glandular epithelia. we found an decreased number of PCNA positive cell and concurrent increase of TUNEL positive cells in the stroma of Lygodium japonicum treated rats (P<0.01). Conclusions : These findings suggest that Lygodium japonicum may protect the glandular epithelial cells and also inhibit stromal proliferation in association with suppression of cyto-proliferation and stimulation of apoptosis. We concluded that Lygodium japonicum could be a useful remedy agents for treating chronic non-bacterial prostatitis.

• Journal of Preventive Medicine and Public Health
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• v.35 no.2
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• pp.99-106
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• 2002

Objective : Until now, there have been no evidence-based guidelines produced for the mass screening of hyperlipidemia cases in Korea. This study was done to find the most efficient strategy for a hyperlipidemia-screening program among Korean adults, Method : Seven alternative strategies for hyperlipidemia screening were formulated and compared ir terms of cost-effectiveness. Cost and effectiveness were estimated from social perspectives and using a two-stage screening process (initial testing and additional testing for positives from the first test). A computerized database (based on persons who had visited a health promotion center in one teaching hospital for a routine health check-up) was used to determine the cost and the outcome of various strategies. Official data was used in calculating direct and indirect costs. Effectiveness was measured according to the number of persons who needed clinical intervention for hyperlipidemia. A stratified analysis, considering age group and sex, was then done. Sensitivity analyses, focusing on several uncertain parameters, were also done. Results : Of the seven test alternatives available, the most cost-effective strategy was a screening program, which consisted of an initial test of total cholesterol, high-density lipoprotein cholesterol and triglyceride. There was some variation in the rank of the cost-effectiveness ratios for the seven alternatives dependent on age group or gender. Conclusions : Current hyperlipidemia screening practice, for National Health Insurance beneficiaries, tests only the total cholesterol level with a cut-off value of 260mg/dl as an initial screening test. It is not the best strategy for cost-effectiveness, and should be modified. Different screening strategies taking age group and sex into account should be developed and used for the efficient mass screening of hyperlipidemia cases among Korean adults.

• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.34-40
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• 2003

Objective: To analyze the treatment-related parameters after the radiotherapy of T1N0 squamous cell carcinoma of the glottic larynx. Materials and Methods: Between October 1989 and August 2000, 54 patients with histologically proven T1N0 squamous cell carcinoma of the glottic larynx who received definitive radiation therapy in Department of Radiation Oncology, Asan Medical Center were analyzed. They were all males with age ranged from 31 to 80 years (median 61 years). 1997 AJCC stages were 31 T1a, 23 T1b. Patients were treated with 4-MV X-rays with a parallel-opposed two-field technique. Ten patients received 66.0-68.4Gy at 1.2Gy per fraction twice daily, 21 patients received 64.8-66.6Gy at 1.8Gy per fraction once daily, and 23 patients received 66.0Gy at 2.0Gy per fraction once daily. Follow-up period was 16-119 months (median 56 months). Results: 5-year overall survival and local control rates for patients with T1 lesions were 87.0% and 88.5%, respectively. 5-year local control with larynx preservation rate was 90.5%. Host and tumor-related prognostic factors including age, stage, anterior commissure involvement and tumor bulk proved not to be significant. Only shorter overall treatment time among treatment-related factors had correlation with imporved local control. Conclusion: Comparable high local control rate with organ preservation was achieved with primary radiation therapy and salvage surgery. Shortening of overall treatment time is related to improved local control rate. To determine the optimal fractionation scheme, randomized trial is mandatory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.135-142
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• 2017

This study employs an analytical mathematical model to estimate the optimal debt ratio of Korean agricultural corporations, more sensitive to the government debt ratio policy compared to other industries, and the estimation of the optimal debt ratio based on objective data. The analytical model utilizes the equation for ROE, with the debt ratio as an independent variable, and related parameters include ROS, TAT, and NFCL. Regarding the NFCL, the optimal debt ratio standard is defined as the debt ratio that maximizes the ROE by analytical procedures such as adding an equation concerning the debt ratio and a linearity relationship to the analytical model, and from these equations, a quadratic equation with the debt ratio as an independent variable describes the ROE. This methodemploys fourteen years of corporate data. Results show that 138% of debt ratio is the optimal debt ratio to increase the ROE of the corporations, which implies that the existing debt ratio of Korean agricultural corporations is higher than optimal. Consequently, it is required for authorities to change future debt ratio policies in view that the purpose of debt ratio management is to maintain safety and increase profitability.Management should emphasize characteristics of the specific industry rather than standardized judgements based on numerical indexes.

• Journal of Korean Neurosurgical Society
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• v.29 no.4
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• pp.536-542
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• 2000

Objective : This study was performed to evaluate the relationships among intracranial pressure(ICP), cerebral perfusion pressure(CPP), and cerebral arteriovenous oxygen difference($AVDO_2$) which were used as parameters of adequacy of cerebral blood flow to support cerebral metabolism after severe head injury and also to examine the association between delayed cerebral infarction and outcome. Material and Method : The authors studied the ICP, CPP and $AVDO_2$ before and after treatment on 34 head-injured patients from June 1996 to December 1997 and examined the association with the change of an ICP, CPP and $AVDO_2$ following treatment and the development of delayed cerebral infarction. Sixteen patients underwent craniotomy for hematoma evacuation and eighteen patients received mannitol to decrease ICP. Results : The development of delayed cerebral infarction was demonstrated in 3(42.9%) out of 7 patients in no improvement group and 13(48.1%) out of 27 patients in improvement group with an increased ICP following treatment. Also, the development of delayed cerebral infarction was demonstrated in 8(50%) out of 16 patients in no improvement group and 8(44.4%) out of 18 patients in improvement group with a decreased CPP following treatment. The association with changes of ICP and CPP following treatment and development of delayed cerebral infarction was not statistically significant(p>0.01). However, 11(78.6%) out of 14 patients who demonstrated an increase in $AVDO_2$ and 5(25%) out of 20 patients who demonstrated a decrease in $AVDO_2$ following treatment developed delayed cerebral infarction. No improvement(reduction) in $AVDO_2$ following treatment was significantly associated with the development of delayed cerebral infarction(p<0.01). All of 16 patients with delayed cerebral infarction showed poor prognosis. Conlcusion : The change of $AVDO_2$ rather than those of ICP and CPP was considered more important factor for the development of the delayed cerebral infarction and poor outcome.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.753-760
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• 2018

Objective : We investigated the effect of optimization in dose-limiting shell method on the dosimetric quality of CyberKnife (CK) plans in treating brain metastases (BMs). Methods : We selected 19 BMs previously treated using CK between 2014 and 2015. The original CK plans ($CK_{original}$) had been produced using 1 to 3 dose-limiting shells : one at the prescription isodose level (PIDL) for dose conformity and the others at low-isodose levels (10-30% of prescription dose) for dose spillage. In each case, a modified CK plan ($CK_{modified}$) was generated using 5 dose-limiting shells : one at the PIDL, another at intermediate isodose level (50% of prescription dose) for steeper dose fall-off, and the others at low-isodose levels, with an optimized shell-dilation size based on our experience. A Gamma Knife (GK) plan was also produced using the original contour set. Thus, three data sets of dosimetric parameters were generated and compared. Results : There were no differences in the conformity indices among the $CK_{original}$, $CK_{modified}$, and GK plans (mean 1.22, 1.18, and 1.24, respectively; p=0.079) and tumor coverage (mean 99.5%, 99.5%, and 99.4%, respectively; p=0.177), whereas the $CK_{modified}$ plans produced significantly smaller normal tissue volumes receiving 50% of prescription dose than those produced by the $CK_{original}$ plans (p<0.001), with no statistical differences in those volumes compared with GK plans (p=0.345). Conclusion : These results indicate that significantly steeper dose fall-off is able to be achieved in the CK system by optimizing the shell function while maintaining high conformity of dose to tumor.

• Journal of the Korean Arthroscopy Society
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• v.4 no.2
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• pp.105-110
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• 2000

Purpose : The purpose of this study was to evaluate the clinical results of fresh-frozen achilles allograft PCL reconstruction. Materials and Methods : 34 patients(35 cases) who was reconstructed PCL arthroscopically using achilles allograft were analyzed subjective and objective parameters, Telos stress arthrometer and Modified Feagin Scoring System. The average age was 36.2 years old($16\~57$ year) and average follow up period was 18.5 months($12\~27$ months). Result : The mean Lysholm Knee Scoring was improved from 47.5 to 87.4. Posterior translation by Telos arthrometer decreased to 2.3mm from 7.1mm. The modified Feagin scoring system showed 32 cases$(91.5\%)$ with excellent and good result. Conclusion : Clinical results of PCL reconstruction by Achilles allograft revealed good result as to scales. Achilles allograft provided enough initial tension with length and minimized the complication of using autograft. Therefore achilles fresh-frozen allograft in PCL reconstruction is a good substitute material for autograft.