• Steel and Composite Structures
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• v.35 no.6
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• pp.799-813
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• 2020

Fatigue cracks of rib-to-deck (RD) joints have been frequently observed in the orthotropic steel decks (OSD) using conventional U-ribs (CU). Thickened edge U-rib (TEU) is proposed to enhance the fatigue strength of RD joints, and its effectiveness has been proved through fatigue tests. In-depth full-scale tests are further carried out to investigate both the fatigue strength and fractography of RD joints. Based on the test result, the mean fatigue strength of TEU specimens is 21% and 17% higher than that of CU specimens in terms of nominal and hot spot stress, respectively. Meanwhile, the development of fatigue cracks has been measured using the strain gauges installed along the welded joint. It is found that such the crack remains almost in semi-elliptical shape during the initiation and propagation. For the further application of TEUs, the design curve under the specific survival rate is required for the RD joints using TEUs. Since the fatigue strength of welded joints is highly scattered, the design curves derived by using the limited test data only are not reliable enough to be used as the reference. On this ground, an experiment-numerical hybrid approach is employed. Basing on the fatigue test, a probabilistic assessment model has been established to predict the fatigue strength of RD joints. In the model, the randomness in material properties, initial flaws and local geometries has been taken into consideration. The multiple-site initiation and coalescence of fatigue cracks are also considered to improve the accuracy. Validation of the model has been rigorously conducted using the test data. By extending the validated model, large-scale databases of fatigue life could be generated in a short period. Through the regression analysis on the generated database, design curves of the RD joint have been derived under the 95% survival rate. As the result, FAT 85 and FAT 110 curves with the power index m of 2.89 are recommended in the fatigue evaluation on the RD joint using TEUs in terms of nominal stress and hot spot stress respectively. Meanwhile, FAT 70 and FAT 90 curves with m of 2.92 are suggested in the evaluation on the RD joint using CUs in terms of nominal stress and hot spot stress, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2078-2087
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• 2010

This study conducted a chi-square test and a logistic regression analysis by not only using a investigation data of discharged patients with damages from 2004 to 2006, but also using a census and a research data on the actual condition from health care system. The result follows; First, the centralization of medical utilization of operation patients is becoming apparent, centrally the capital area. To improve this, a policy that can not only provide medical centers and sickbed, but also improve the quality of local medical treatments for the localization of medical treatments. Second, propelling localization policy of certain diseases for the localization of medical utilization is needed as the rate of non-residential of operation patients that have diseases of the eye and adnexa, or cancers is high. Third, a localization policy for patients with damages is needed as the rate of treatments in other regions of operation patients with industrial accidents is increasing day by day.

• International Commerce and Information Review
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• v.16 no.1
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• pp.25-42
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• 2014

Since the reform and opening up in 1978, Chinese economy has been increasing rapidly with a high growth rate, but after 2012 the growth rate decreased as the reform of economic system. While economy in Africa began booming since 2000. Influenced by Global Financial Crisis and European Debt Crisis, economy in Africa slightly slowed down, but it was rebounding apparently from 2010. The urgent demand for energy and the sharp increasing in foreign exchange reserve pushes China to seek overseas markets. As Africa keeps a well relationship with China and the complementarity between China and Africa economy, Africa becomes one of the target markets for China's foreign development. Recently more and more enterprises begin to invest in Africa market. But till now the study on Africa mainly focuses on theoretical research based on real cases, and empirical research are very few and need to be increased. This thesis studies the influence of enterprise feature; local market feature and investment in foreign market on the result satisfaction of Chinese enterprises that invest in Africa markets. At the same time this thesis also studies and analyzes the market access strategy and marketing strategy for Chinese enterprises after entering overseas markets and put forward effective recommendation and suggestion for these enterprises. In order to proceed this study, 317 Chinese enterprises which invest in Africa have been investigated by me. And frequency analysis, reliability analysis, factor analysis, and simple regression analysis have also been conducted by SPSS18.0 APP to verify the hypothesis. The study result suggests that onlu investment in foreign market affects the Performance satisfaction of Chinese enterprises. And the market access strategy and marketing strategy play a role of the mediational effects when Chinese enterprises are investing in Africa.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4381-4389
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• 2016

Background: Surgery is the corner stone for the management of rectal cancer. The purpose of this study was to demonstrate the optimal time of surgical resection after the completion of neoadjuvant chemo-radiotherapy (CRT) in treatment of locally advanced rectal cancer. Materials and Methods: This study compared 2 groups of patients with locally advanced rectal cancer, treated with neoadjuvant CRT followed by surgical resection either 6-8 weeks or 9-14 weeks after the completion of chemo-radiotherapy. The impact of delaying surgery was tested in comparison to early surgical resection after completion of chemo-radiotherapy. Results: The total significant response rate that could result in functional preservation was estimated to be 3.85% in group I and 15.4% in group II. Some 9.62% of our patients had residual malignant cells at one cm surgical margin. All those patients with positive margins at one cm were in group I (19.23%). There was less operative time in group II, but the difference between both groups was statistically insignificant (P=0.845). The difference between both groups regarding operative blood loss and intra operative blood transfusion was significantly less in group II (P=0.044). There was no statistically significant difference between both groups regarding the intra operative complications (P=0.609). The current study showed significantly less post-operative hospital stay period, and less post-operative wound infection in group II (P=0.012 and 0.017). The current study showed more tumor regression and necrosis in group II with a highly significant main effect of time F=61.7 (P<0.001). Pathological TN stage indicated better pathological tumor response in group II (P=0.04). The current study showed recurrence free survival for all cases at 18 months of 84.2%. In group I, survival rate at the same duration was 73.8%, however none of group II cases had local recurrence (censored) (P=0.031). Disease free survival (DFS) during the same duration (18 months) was 69.4 % for patients in group I and 82.3% for group II (P=0.429). Conclusions: Surgical resection delay up to 9-14 weeks after chemo-radiation was associated with better outcome and better recurrence free survival.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.31-40
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• 2012

The irregularity of railway track affects not only the comfort of ride such as noise or vibration but also the safety of train operation. For this reason, it is an interesting research area to design a reliable and sustainable railway track system and to analyze the train movement mechanism based on systematic approaches considering reasons of track irregularity possible in a specific local environment. Irregularity data inspected by EM-120, an railway inspection system in Korea includes unavoidable incomplete and erratic information, so it is encountered lots of problem to analyse those data without appropriate pre-data-refining processes. In this research, for the efficient management and maintenance of railway system, progress rate of standard deviation of irregularity is quantified. During the computation, some important components of railways such as rail joint, ballast, roadbed, and fastener have been considered. Probabilistic distributions of irregularity growth with respect to time are computed to predict the remaining service life of railway track and to be adapted for the safety assessment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.104-115
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• 2016

Objective: This study was conducted in order to investigate the effects of individual patient behavior regarding the health and medical care level on their therapeutic compliance for people diagnosed with high blood pressure by a physician, in order to evaluate the impact of treatment compliance. In this study, the therapeutic compliance was defined as the hypertension drug cure rate. The current blood pressure controls were persons about 30 years of age diagnosed with high blood pressure by their doctor one month fraction of the people who take more than 20 days (30 days). Methods: The data was analyzed by using the X2-test for different comparisons of the therapeutic compliance in the individual characteristics and using a two-stage multilevel logistic regression to identify the community variance of the related index of high blood pressure therapeutic compliance using the data from 229 adults over the age of 19 in a community health survey conducted in 2010. The Spss 18.0 statistical program was used with HLM 7 (hierarchical linear model) Results: It was found that the rate of therapeutic compliance was affected by the individual health behavior and health and medical care levels. Conclusion: In this study, although the odds ratio of the variable region of the high level of health care, I was able Unlike previous studies and focuses on the personal level of variation found variations in the local health care level was a significant. More studies on multilevel analysis are needed in the future considering regional level data.

• Journal of agricultural medicine and community health
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• v.46 no.4
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• pp.253-265
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• 2021

Objectives: The aim of the study is to identify the success factors of 6 months of smoking cessation targeting male workers in small and medium-sized businesses. Methods: The subjects of this study were smoking male workers who had got the visiting services at a tobacco control center to stop smoking from January 2018 to December 2020. Total number of the participants was 767. Results: The male workers in small and medium enterprises had a success rate of 20.2% for smoking cessation for 6 months. With multiple logistic regression, the factors causing the differences in the success rate for 6 months of the workers were as follows. - The odds ratios (ORs)(95% confidence interval, CI) of the age group of under 29 and 40-49 years were 0.10 (0.03-0.29) and 0.43 (0.24-0.76), respectively, compared to the 50 years and older group. The ORs (95% CI) of the daily average of smoking group of 11-20 and more than 21 were 0.52(0.34-0.80) and 0.46(0.24-0.90), respectively, when compared to the group of 1-10. The ORs (95% CI) of the supporting persons for quitting smoking group of with spouse and other family were 1.99(1.18-3.34), compared to the group with no one. Conclusions: This study showed that the chance of success for smoking cessation for 6 months is higher when the subjects have spouses and other family Supporting persons for quitting smoking. And it also shows that the less they smoke a day and the older they are, the more likely it is to succeed in quitting smoking.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.558-571
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• 2022

Objective : The primary objective of this study was to identify predicting factors for local control (LC) of atypical meningioma, and we validated them with comparing the predicting factors for recurrence-free survival (RFS). We also examined the rate of LC after surgical resection with or without adjuvant treatment and RFS. Methods : Clinical and radiological records of patients with atypical meningiomas diagnosed at two institutes from January 2000 to December 2018 were reviewed retrospectively. Histopathological features were also reviewed using formalin-fixed paraffin embedded samples from pathological archives. Results : Of the 99 atypical meningiomas eligible for analysis, 36 (36.4%) recurred during the follow-up period (mean, 83.3 months; range, 12-232 months). The rate of 3-year LC and 5-year LC was 80.8% and 74.7%, respectively. The mean time-to-recurrence was 49.4 months (range, 12-150). The mean RFS was 149.3 months (95% confidence interval, 128.8-169.8 months) during the mean follow-up duration of 83.3 months (range, 12-232 months). Multivariate analysis using Cox proportional-hazard regression model showed that the extent of resection (hazard ratio [HR], 4.761; p=0.013), Ki67 index (HR, 8.541; p=0.004), mitotic index (HR, 3.275; p=0.044), and tumor size (HR, 3.228; p=0.041) were independently associated with LC. These factors were also statistically associated with RFS. In terms of radiotherapy after surgical resection, the recurrence was not prevented by immediate radiotherapy because of the strong effect of proliferative index on recurrence. Conclusion : The present study suggests that the extent of resection, proliferative index (according to Ki67 expression) and mitotic index, and tumor size are associated with recurrence of atypical meningiomas. However, our results should be further validated through prospective and randomized clinical trials to overcome the inborn bias of retrospective nature of the study design.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.52-68
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• 1991

A new propeller series is developed using the newly developed blade section(KH18 section) which behaves better cavitation characteristics and higher lift-drag ratio at wide range of angle-of-attack. The pitch and camber distributions are disigned in order to have the same radial and chordwise loading distribution with the selected circumferentially averaged wake input. Since the geometries of the series propeller, such as chord length, thickness, skew and rate distribations, are selected by regression of the recent full scale propeller geometric data, the performance prediction of a propeller at preliminary design stage can be mure realistic. Number of blades of the series propellers is 4 and the expanded blade area ratios are 0.3, 0.45, 0.6 and 0.75. Mean pitch ratios are selected as 0.5, 0.65, 0.8, 0.75 and 1.1 for each expanded area ratio. The new propeller series is composed of 20 propellers and is named as KD(KRISO-DAEWOO) propeller series. Propeller open water tests are performed at the experimental towing tank, and the cavitation observation tests and fluctuating pressure measurements are carried out at the cavitation tunnel of KRISO. $B_{P}-\delta$ curves, which can be used to select the optimum propeller diameter at the preliminary design stage, are derived from a regression analysis of the propeller often water test results. The KD-cavitation chart is derived from the cavitation observation test results by choosing the local maximum lift coefficient and the local cavitation number as parameters. The caviy extent of a propeller can be predicted more accurately by using the KD-cavitation chart at a preliminary design stage, since it is derived from the results of the cavitation observation tests in the selected ship's wake, whereas the existing cavitation charts, such as the Burrill's cavitation chart, are derived from the test results in uniform flow.

• Radiation Oncology Journal
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• v.23 no.3
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• pp.143-156
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• 2005

Background: The best dose-fractionation regimen of the definitive radiotherapy for cervix cancer remains to be clearly determined. It seems to be partially attributed to the complexity of the affecting factors and the lack of detailed information on external and intra-cavitary fractionation. To find optimal practice guidelines, our experiences of the combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT) were reviewed with detailed information of the various treatment parameters obtained from a large cohort of women treated homogeneously at a single institute. Materials and Methods: The subjects were 743 cervical cancer patients (Stage IB 198, IIA 77, IIB 364, IIIA 7, IIIB 89 and IVA 8) treated by radiotherapy alone, between 1990 and 1996. A total external beam radiotherapy (EBRT) dose of $23.4\~59.4$ Gy (Median 45.0) was delivered to the whole pelvis. High-dose-rate intracavitary brachytherapy (HDR-IBT) was also peformed using various fractionation schemes. A Midline block (MLB) was initiated after the delivery of $14.4\~43.2$ Gy (Median 36.0) of EBRT in 495 patients, while In the other 248 patients EBRT could not be used due to slow tumor regression or the huge initial bulk of tumor. The point A, actual bladder & rectal doses were individually assessed in all patients. The biologically effective dose (BED) to the tumor ($\alpha/\beta$=10) and late-responding tissues ($\alpha/\beta$=3) for both EBRT and HDR-ICBT were calculated. The total BED values to point A, the actual bladder and rectal reference points were the summation of the EBRT and HDR-ICBT. In addition to all the details on dose-fractionation, the other factors (i.e. the overall treatment time, physicians preference) that can affect the schedule of the definitive radiotherapy were also thoroughly analyzed. The association between MD-BED $Gy_3$ and the risk of complication was assessed using serial multiple logistic regression models. The associations between R-BED $Gy_3$ and rectal complications and between V-BED $Gy_3$ and bladder complications were assessed using multiple logistic regression models after adjustment for age, stage, tumor size and treatment duration. Serial Coxs proportional hazard regression models were used to estimate the relative risks of recurrence due to MD-BED $Gy_{10}$, and the treatment duration. Results: The overall complication rate for RTOG Grades $1\~4$ toxicities was $33.1\%$. The 5-year actuarial pelvic control rate for ail 743 patients was $83\%$. The midline cumulative BED dose, which is the sum of external midline BED and HDR-ICBT point A BED, ranged from 62.0 to 121.9 $Gy_{10}$ (median 93.0) for tumors and from 93.6 to 187.3 $Gy_3$ (median 137.6) for late responding tissues. The median cumulative values of actual rectal (R-BED $Gy_3$) and bladder Point BED (V-BED $Gy_3$) were 118.7 $Gy_3$ (range $48.8\~265.2$) and 126.1 $Gy_3$ (range: $54.9\~267.5$), respectively. MD-BED $Gy_3$ showed a good correlation with rectal (p=0.003), but not with bladder complications (p=0.095). R-BED $Gy_3$ had a very strong association (p=<0.0001), and was more predictive of rectal complications than A-BED $Gy_3$. B-BED $Gy_3$ also showed significance in the prediction of bladder complications in a trend test (p=0.0298). No statistically significant dose-response relationship for pelvic control was observed. The Sandwich and Continuous techniques, which differ according to when the ICR was inserted during the EBRT and due to the physicians preference, showed no differences in the local control and complication rates; there were also no differences in the 3 vs. 5 Gy fraction size of HDR-ICBT. Conclusion: The main reasons optimal dose-fractionation guidelines are not easily established is due to the absence of a dose-response relationship for tumor control as a result of the high-dose gradient of HDR-ICBT, individual differences In tumor responses to radiation therapy and the complexity of affecting factors. Therefore, in our opinion, there is a necessity for individualized tailored therapy, along with general guidelines, in the definitive radiation treatment for cervix cancer. This study also demonstrated the strong predictive value of actual rectal and bladder reference dosing therefore, vaginal gauze packing might be very Important. To maintain the BED dose to less than the threshold resulting in complication, early midline shielding, the HDR-ICBT total dose and fractional dose reduction should be considered.