• Radiation Oncology Journal
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• v.13 no.2
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• pp.143-148
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• 1995

Purpose: We tried to evaluate the role of conventional radiotherapy alone or with neoadjuvant chemotherapy in the hypopharyngeal cancer by retrospective analysis. Materials and Methods: Between Jul.1985 and Sep.1992, 42 patients of hypopharyngeal cancer were treated by conventional radiotherapy alone or combined with neoadjuvant chemotherapy. The male to female ratio was 20:1 with a median age of 58 years, Twelve Patients were treated by conventional radiotherapy alone and 30 patients were treated by neoadjuvant chemotherapy and radiotherapy. Results: Seven Patients were Stage I,II and the patients with stage III and IV were 10 and 25, respectively at the time of presentation. The overall survival and disease-specific survival rates at 24 months were $12.9\%$ and $15.5\%,$respectively Two-year survival rates of stage I+II and III+IV patients were $50\%$ and $6.3\%,$ respectively(p(0.05). Sixteen Patients$(38\%)$ revealed CR and 26 patients$(62\%)$ revealed less than CR at the end of radiotherapy and their 2-year survival rates were $31.3\%\;and\;0\%,$ respectively(p(0.05). On univariate analysis, stage, T-stage, N-stage and treatment response were the significant prognostic factors, but only stage and treatment response were significant on multivariate analysis Conclusion : This conventional radiotherapy alone or with neoadjuvant chemotherapy does not seem to be sufficient in the treatment of most advanced hypopharyngeal cancer Therefore other treatment modalities such as hyperfractionation or concurrent chemoradiotherapy should be considered.

• Journal of Powder Materials
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• v.25 no.1
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• pp.7-11
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• 2018

In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.22-30
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• 2008

In this paper, we deal with modulation classification method using WT capable of classifying incident digital signals without a priori information. These key features should have good properties of sensitive with modulation types and insensitive with SNR variation. The 4 key features for modulation recognition are selected using WT coefficients, which have the property of insentive to the changing of noise. The numerical simulations for classifying 8 digital modulation types using these features are peformed. The numerical simulations of the 3 types (i.e. DTC, MDC, and SVMC) of modulation classifiers are performed the investigation of classification accuracy and execution time to design the modulation classification module in software radio. The simulation result indicated that the execution time of MDC and DTC was best and MDC and SVMC showed good classification performance.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.51-60
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• 2016

In determining a shear wave velocity (Vs) profile model based on field tests for dams, the uncertainties always exist. These uncertainties are caused by spatial variations of material properties in each dam and between dams and should be considered in determining Vs profile model for dams. In this paper, these uncertainties are evaluated and Vs profile model for core zone of fill dam in Korea is proposed using the shear wave velocity profiles determined in seven fill dams. The proposed Vs profile model is compared with Kim's model and Sawada-Takahashi model widely used for evaluation of Vs profile of core zone of fill dam.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.73-81
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• 2005

We propose an automatic modulation recognition scheme which extracts pre-defined key features from the received signal and then applies equal gain combining method to determine the used modulation. Moreover, we compare and analyze the performance of the proposed algorithm with that of decision-theoretic algorithm. Our scheme extracts five pre-defined key features from each data segment, a data unit for the key feature extraction, which are then averaged over all the segments to recognize the modulation according to the decision procedure. We check the performance of the proposed algorithm through computer simulations for analog modulations such as AM, FM, SSB and for digital modulations such as FSK2, FSK4, PSK2, and PSK4, by measuring recognition success rate varying SNR and data collection time. The result shows that the performance of the proposed scheme is comparable to that of the decision-theoretic algorithm with less complexity.

• The Journal of Information Systems
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• v.15 no.4
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• pp.73-98
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• 2006

The purpose of this study was to verify and analyze the factors that influence the acceptance intention of u-Commerce users under ubiquitous computing environments. To accomplish this, the Technology Acceptance Model(TAM) of Davis(1989), which has widely been cited in new technologies such as information technology(IT) and information systems(IS) studies was used to develop the research model. First of all, personal characteristics affecting the acceptance intention of u-Commerce were identified as individual variables through literature review. Utilizing the use of the individual variables and the TAM model, the u-Commerce acceptance intention model was established. The research findings indicated that IT acceptance forms and frequencies in IT use did not have a significant impact on perceived usefulness and perceived ease of use of u-Commerce. It was also found that the perceived usefulness proposed in the u-Commerce acceptance model influenced the perceived usefulness. Both ease of use and usefulness were identified to influence attitude for use. Finally, usefulness and attitude for use also positively influenced acceptance intention. The contribution of this study was the examination of the factors affecting acceptance intention of users in u-Commerce and the verification of the usefulness of the TAM model in describing the acceptance of u-Commerce users using structure acceptance model. Furthermore, this study has empirically analyzed how personal characteristics widely used in the study of acceptance of IT can influence the acceptance of u-Commerce.

• Elastomers and Composites
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• v.45 no.1
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• pp.40-43
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• 2010

In this study, polyimide(PI) nanofibers mats were prepared by electrospinning and three different fiber morphologies of random, uniaxial, and biaxial orientation were prepared by controlling the speed of drum-shaped collector and other parameters. The SEM studies reveal that the aforesaid morphologies were obtained on the nano-fibrous mats prepared. The ionic conductivity was measured using an in-plane type conductivity tester for the PI mats soaked in the mixture of 1M lithium trifluoro-methane-sulfonate and tetra-ethylene glycol dimethyl ether. The ionic conductivity was surprisingly higher for the biaxial PI mats. For the uniaxially-oriented mats, the ionic conductivity was found to be higher in the parallel direction compared to the perpendicular direction of the fiber orientation. A curious cyclic fluctuation was found in the ionic conductivity with time. The observed behavior was explained by considering the distance between fibers and transport speed of ions used in this study.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.365-380
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• 2016

Purpose: The purpose of this study was to ascertain the need to reform curriculums for digital experts in a way that include the practical and educational aspects of dental labs by determining why educational reforms are needed to comply with changes in dental technology business that are brought by the applications of digital scanning and what changes are being actually brought by the use of CAD/CAM. Methods: This study analyzed the need of education and practice in relation to CAD/CAM by using the independent sample t-test and One-way ANOVA. in accordance with the participants demographic characteristics and job-related variables and factors related to CAD/CAM, and provided only some of the analysis results that were found statistically significant. Concerning the need of education and practice in relation to CAD/CAM, the study also used the independent sample t-test to measure difference in the perception of that need within each of the three groups, or those of job performance, job efficiency and knowledge gain at the signficance level of ${\alpha}=.05$. Results: Dental technologists surveyed here were perceiving that the use of CAD/CAM would bring changes in their job performance, job efficiency and knowledge gain. They were expecting that the biggest changes would be made in work climate and product quality as sub-areas of job performance. However, they said that in terms of job efficiency, the use of CAD/CAM would change job contribution, job satisfaction and job efficiency, but not lead to staffing. These results suggest that more special programs for CAD/CAM education are needed to bring up CAD/CAM experts who are more specialized. Conclusion: Among 13 skills related to CAD/CAM, what is most needed to be educated to dental technologists was "molding the occlusal surface" (M=4.19), followed by "designing the 3-D work" (M=4.17), "final shape modification" (M=4.16), "molding the border" (M=4.15) and "checking the fit of prothesis" (M=4.14) in order.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.786-795
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• 2010

In this paper, we propose a new EBG structure that the two unit cells are connected by the bridge line in signal transmission plane. The SSN of the power plane is reduced effectively by via holes and bridge lines connecting the unit cells. The superior signal transfer characteristic is shown between the signal lines in the signal transmission plane. The proposed EBG structure contains 1.2 GHz cut-off frequency and less than －30 dB suppression in the 8.3 GHz broad bandwidth. In addition, To improve the SI(Signal Integrity) in signal transmission plane keeping the same bandstop frequency range, the optimized location of the reference plane is proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.127-134
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• 2011

It has been reported that the length parameter of high strength bolts results in the variance in tensile loads. The required turn of nut for each length is specified in AISC RCSC specification. There is no specific regulation datum about the bolt length in the two national codes and specifications in Korea. Therefore this study focused on evaluating influence of the clamping torque subjected to length parameter of high strength bolts. Two types of high strength bolt specimens were manufactured and tested; High Strength Hexagon bolt specified in ASTM A490 and Torque Shear Bolt in KS B 2819. The length parameter ranged from 60mm(3d) to 140mm(7d). The torque, turn of nut, and the clamping force were analyzed to review whether length parameter affects on the required tensile strength. To evaluate the effects of the length parameter on the torque and turn of nut for the required strength and clamping force, statistical analysis was also carried out.