• Hwankyungkyoyuk
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• v.20 no.4
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• pp.117-131
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• 2007

The objectives of this study were to investigate using environment-friendly agricultural products and to analyze consciousness of agricultural safety of consumers. The data were collected from 1,000 consumers by two-staged stratified random sampling. SPSSWIN/ver. 13 program was used for analyzing data with frequency, cross-tab, t-test and ANOVA. The major findings of this study were as follows: 1) Consumers with higher academic career, more income, and white collars showed higher experiences on environment-friendly agricultural products. 2) Consumers who are under thirties, university graduation and upper income revealed high intention to use environment-friendly agricultural products. 3) The study revealed information needs and information acquisition are significantly different among consumers 4) Consumers with higher academic and upper income showed higher agricultural safety concern, 5) The study discovered that consumers who are over sixties and under middle school graduation were higher on agricultural safety effects.

• Journal of Chest Surgery
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• v.27 no.7
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• pp.598-602
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• 1994

We have experinced 20 cases of esophageal perforation from April, 1987 to August, 1993 at ourdivision of Thoracic and Cardiovascular Surgery, Korea University, Gu Ro Hospital. Here we investgates the causes of disease, symptoms and sign, locations, time lag from onset, treatment of perforation and the results.The ratio between male and female patients was 12: 8, and age ranged from 4 years to 70 years old.The cause of esophageal perforation were instrumental trauma 7 cases, stab wound 4 cases, foreign body 4 cases, spontaneous perforations 3 cases, and others 1 cases. The middle and lower portions of esophagus was frequently involved portion in our cases [11 cases of 20].The common complications after perforation were mediastinitis [6 cases] and empyema [2 cases].The method of treatment were as follows, primary repair of perforation, simple drainge techniques including simple cervical drainage and closed thoracostomy, diversion and two-staged operations during several months. There was no mortality in our cases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1195-1201
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• 2009

In this study, effective methods for reliability estimation and reliability-based design optimization(RBDO) are proposed using kriging metamodel and genetic algorithm. In our previous study, we proposed the accurate method for reliability estimation using two-staged kriging metamodel and genetic algorithm. In this study, the possibility of applying the previously proposed method to RBDO is investigated. The efficiency and accuracy of that method were much improved than those of the first order reliability method(FORM). Finally, the effective method for RBDO is proposed and applied to numerical examples. The results are compared to the existing RBDO methods and shown to be very effective and accurate.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.687-694
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• 2018

To investigate the crushing behaviour of coarse granular materials, a specifically designed, large-scale simple shear apparatus with eight-staged shearing rings was developed. A series of monotonic simple shear tests were conducted on two kinds of coarse granular materials under different vertical stresses and large shear strains. The evolution of the particle breakage during the compression and simple shearing processes was investigated. The results show that the amount of particle breakage is related to the particle hardness and the state of the stresses. The amount of particle breakage is greater for softer granular materials and increases with increasing vertical stresses. Particle breakage may tend towards a critical value during both the compression and the shearing processes. Particle breakage mainly occurs during the processes of confined compression and contraction.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1016-1021
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• 2008

In this study, effective methods for reliability estimation and reliability-based design optimization(RBDO) are proposed using kriging metamodel and genetic algorithm. In our previous study, we proposed the accurate method for reliability estimation using two-staged kriging metamodel and genetic algorithm. In this study, the possibility of applying the previously proposed method to RBDO is examined. The accuracy of that method is much improved than the first order reliability method with similar efficiency. Finally, the effective method for RBDO is proposed and applied to numerical examples. The results are compared to the existing RBDO methods and shown to be very effective and accurate.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.3
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• pp.181-188
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• 2009

Hundreds of thousands of South Korean protesters staged candlelight vigils and demonstrations against US beef imports in 2008. The problems, however, went far beyond that of beef imports. The political party veterans, who lost the presidential election, exploited labor unions that were discontent with the economy and ideological student groups to weaken the majority party. In this study, an epidemiological model is constructed with a system of three nonlinear differential equations. The model seeks to examine the dynamics of the system through stability analysis. Two threshold conditions that spread the protests are identified and a sensitivity analysis on the conditions is performed to isolate the parameters to which the system is most responsive. The results are also explored by deterministic simulations. This model can be easily modified to apply to other protests that may occur in various circumstances.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.636-641
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• 2010

A preburner for the staged combustion in the high performance liquid rocket engine is being developed and strength experiments and finite element analyses on specimens, which simulate the brazing joint of the preburner, were performed and the results were compared. One specimen simulate the joints near oxygen injectors of head by the funance brazing and two specimens the joints of the combustion chamber cooling channel by vacuum brazing. The experiments were burst ones with strain gauges.

• Journal of Korean Neurosurgical Society
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• v.38 no.3
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• pp.245-247
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• 2005

Most chordomas show extradural extension and bone destruction. A 32-year-old man presented with neck pain and progressive paraparesis. He had been diagnosed a clival chordoma and underwent an operation seven years ago. Radiological studies revealed that the tumor was recurred in a retroclival area and invaded into intradural region. We removed the tumor by two staged operations. After surgery, satisfactory results were achieved.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3747-3750
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• 2013

Purpose: To evaluate the efficacy of conservative surgery plus chemo-, radio-therapy in treating patients with early stage breast cancer. Patients and Methods: Eligible patients were treated by postoperative chemotherapy as well as whole-breast irradiation with tumor bed boost. Postoperative radiotherapy consisted of 6 MV whole breast linear accelerator irradiation with two tangential half fields to a total dose of 45~50 Gy, followed by $10{\sim}15MeV{\beta}$ boost irradiation to tumor bed for 10~20Gy, total dose 56~66Gy. Results: Fifty-two patients were enrolled. Overall 1-, 2- and 3 year survival rates were 98.1%, 92.3%, and 90.4%, respectively, with a local recurrence rate of 5.77%. Cosmetic results were evaluated as good by doctors in 90.4% of patients. Conclusions: Breast conservative surgery combined with chemo- radio-therapy could be a treatment option for Chinese patients with early stage breast cancer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1793-1801
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• 2001

A study of low NOx atomizer was carried out to reduce nitrogen oxides(NOx) in a liquid fuel burner flame. The basic concept of NOx reduction in this atomizer is the fuel 2-staging combustion which is generated by a single atomizer forming two different stoichiometric flames. Two orifices swirl atomizer was selected and modified to realize this concept, and it was tested to obtain the design process of low NOx atomizer. These experiments were achieved to find out the relationship between the injection pressures and the flow rate, spray angle and drop size of swirl atomizer as well as to confirm the NOx reduction concept in real plant(power boiler). In comparison between experimental and theoretical results, the correct discharge coefficient and spray angle were obtained. In real burning test, NOx reduction rate was reached to above 27% of the case using conventional swirl atomizer.