• Communications of the Korean Mathematical Society
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• v.37 no.4
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• pp.1269-1284
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• 2022

This paper is concerned with the following Schrödinger-Poisson system $$\{\begin{array}{lll}-{\Delta}u+V(x)u+K(x){\phi}u=a(x){\mid}u{\mid}^{p-2}u&&\text{ in }{\mathbb{R}}^3,\\-{\Delta}{\phi}=K(x)u^2&&\text{ in }{\mathbb{R}}^3,\end{array}$$ where 4 < p < 6. For the case that K is nonnegative, V and a are indefinite, we prove the above problem possesses one ground state sign-changing solution with exactly two nodal domains by constraint variational method and quantitative deformation lemma. Moreover, we show that the energy of sign-changing solutions is larger than that of the ground state solutions. The novelty of this paper is that the potential a is indefinite and allowed to vanish at infinity. In this sense, we complement the existing results obtained by Batista and Furtado [5].

• Radiation Oncology Journal
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• v.27 no.3
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• pp.126-132
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• 2009

Purpose: We wanted to evaluate the prognostic factors for the pathologic N2 non-small cell lung cancer (NSCLC) patients who were treated by postoperative radiotherapy. Materials and Methods: We retrospectively reviewed 112 pN2 NSCLC patients who underwent surgery and postoperative radiotherapy (PORT) From January 1999 to February 2008. Seventy-five (67%) patients received segmentectomy or lobectomy and 37 (33%) patients received pneumonectomy. The resection margin was negative in 94 patients, and it was positive or close in 18 patients. Chemotherapy was administered to 103 (92%) patients. Nine (8%) patients received PORT alone. The median radiation dose was 54 Gy (range, 45 to 66), and the fraction size was 1.8~2 Gy. Results: The 2-year overall survival (OS) rate was 60.2% and the disease free survival (DFS) rate was 44.7% for all the patients. Univariate analysis showed that the patients with multiple-station N2 disease had significantly reduced OS and DFS (p=0.047, p=0.007) and the patients with an advanced T stage ($\geq$T3) had significantly reduced OS and DFS (p<0.001, p=0.025). A large tumor size ($\geq$5 cm) and positive lymphovascular invasion reduced the OS (p=0.035, 0.034). Using multivariate analysis, we found that multiple-station N2 disease and an advanced T stage ($\geq$T3) significantly reduced the OS and DFS. Seventy one patients (63.4%) had recurrence of disease. The patterns of failure were loco-regional in 23 (20.5%) patients, distant failure in 62 (55.4%) and combined loco-regional and distant failure in 14 (12.5%) patients. Conclusion: Multiple involvement of mediastinal nodal stations for the pN2 NSCLC patients with PORT was a poor prognostic factor in this study. A prospective study is necessary to evaluate the N2 subclassification and to optimize the adjuvant treatment.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.513-518
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• 2011

In this paper, a unified design environment is developed for the optimization of electric machines based on continuum sensitivity. For electromagnetic (EM) system analysis, COMSOL scripting environment is used. Optimization module is developed by MATLAB programming, which can be combined with COMSOL script commands. The modules are combined into one MATLAB project, and iteration process necessary for the optimization of EM system can be performed efficiently. During the design process, visual feedback of the current design status is given to the designer. In addition, the B-Spline parametrization of the nodal points is implemented to obtain smooth boundary of the device. The developed software is applied to the problem of finding uniform flux density distribution at the air gap of an electromagnet to verify its feasibility and effectiveness.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.172-174
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• 2002

This paper proposes a new methodology for adequacy evaluation of composite power system considering an ambiguity of overload of transmission lines. Nodal arrival powers under considering an ambiguity of overload of transmission lines can be evaluated using the proposed method. Fuzzy set theory has been used in order to consider the permission level of overload of transmission lines. The problem of adequacy evaluation has been formulated using fuzzy linear programing. The effectiveness of the proposed method considering permissible overload of transmission lines has been demonstrated on the IEEE RTS.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.24-30
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• 2001

The substructure synthesis method(SSM) is developed for overcoming disadvantages of the Finite Element Method(FEM). The concept of the SSM is as follows. After dividing a whole structure into several substructures, every substructures are analyzed by the FEM or experiment. The whole structure is analyzed by using connecting condition and the results of substructures. The concept of the transfer stiffness coefficient method(TSCM) is based on the transfer of the nodal stiffness coefficients which are related to force vectors and displacement vectors at each node of analytical mode1. The superiority of the TSCM to the FEM in the computation accuracy, cost and convenience was confirmed by the numerical computation results. In this paper, the author suggests an efficient vibration analysis method of structures by using the TSCM and the SSM. The trust and the validity of the present method is demonstrated through the numerical results for computation models.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.42-49
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• 2005

The vibration analysis of a rectangular plate with stiffeners is formulated by using the transfer stiffness coefficient method (TSCM). This method is based on the concept of the successive transmission of stiffness coefficients which are defined as the relationship between the force vector and the displacement vector at an arbitrary nodal line. In order to confirm the validity of the present method, bending vibration analysis for a rectangular plate with stiffener is carried out on a personal computer by using the present method and the finite element method (FEM). Through comparing computational results of the TSCM and the FEM, the effectivness of the TSCM from the viewpoint of computational cost, that is, computational time and storage is demonstrated.

• Korean Journal of Head & Neck Oncology
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• v.3 no.1
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• pp.5-13
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• 1987

Cancer of the head and neck is an uncommon disease accounting for 5 % of all cancers. In an anatomic area so readily visible and palpable for examination without special and expensive diagnositic tools, it is unfortunate that many patients still present with advanced diseases. Since the prognosis is so intimately related to stage of disease, it is very important to detect the earliest stage of cancer with a complete head and neck examination. In the evaluation of cancer at any anatomic site, the description of the extent of the lesion is important. Not only does proper staging of the tumor lead to make decision of the most appropriate treatment, it also serves as a guide for the results of treatment. Proper staging demands a careful clinical assesment of the extent of the cancer. The current staging system for head and neck cancer uses the TNM system devised by American Joint Committee for Cancer Staging and End Result Reporting. T represent the primary tumor, N, regional nodal metastases, and M, distant metastases. The detection, diagnosis, and appropriate treatment of eary cancer will result in improved survival.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.51-58
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• 1997

Determining sizes and the locations of reservoirs in the water distribution system(WDS) with multi-reservoirs is much difficult than that with single reservoir. The extended period simulation(EPS) models provide more comprehensive analysis of water distribution systems than the steady-state models can do. Therefore, EPS models should be applied to the WDS with multi-reservoirs. This study is to investigate the variations of required reservoir sizes and residual nodal pressures according to reservoir locations. In this study, EPS was applied to analyze an artificial and a real WDS under several water demand patterns. As a result, it was found that water demand patterns make no significant differences in the determining of the reservoir size, if they have similar peaking factors. And the variations of the peaking factor should be carefully checked in the design and the analysis of the WDS with multi-reservoirs, because the peaking factor itself will affect the minimum allowable sizes of reservoirs in those systems.

• Coupled systems mechanics
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• v.4 no.4
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• pp.317-336
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• 2015

The present paper deals with the analysis of water tank with elastic separator wall. Both fluid and structure are discretized and modeled by eight node-elements. In the governing equations, pressure for the fluid domain and displacement for the separator wall are considered as nodal variables. A method namely, direct coupled for the analysis of water tank has been carried out in this study. In direct coupled approach, the solution of the fluid-structure system is accomplished by considering these as a single system. The hydrodynamic pressure on tank wall is presented for different lengths of tank. The results show that the magnitude of hydrodynamic pressure is quite large when the distances between the separator wall and tank wall are relatively closer and this is due to higher rotating tendency of fluid and the higher sloshed displacement at free surface.

• Korean Journal of Head & Neck Oncology
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• v.26 no.1
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• pp.14-18
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• 2010

Objectives : We evaluated the use of FDG PET/CT for the identification of cervical nodal metastases of SCC of the oral cavity and oropharynx with histological correlation. Material and Methods : We reviewed 46 medical records, from January 2004 to July 2007, of patients who underwent FDG PET/CT and CT/MRI for SCC of the oral cavity and oropharynx before surgery. We recorded the lymph node metastases according to the neck level affected and the system used for the imaging-based nodal classification. Results : The FDG PET/CT had a sensitivity of 75.6% and a specificity of 96.7% ; it had a higher sensitivity than the CT/MRI for identification of cervical metastases on the side of the neck(26/28 vs. 20/28, p=0.031) and at each of the cervical levels(34/45 vs. 26/45, p=0.008). There was a significant difference in the $SUV_{max}$ between the benign and malignant cervical lymph nodes($3.31{\pm}3.23$ vs. $4.22{\pm}2.57$, p=0.028). The receiver-operating-characteristic (ROC) curve analysis for differentiating the benign from the malignant cervical lymph nodes, showed that the area under the curve(AUC) of the FDG PET/CT was 0.775. The cut-off value for the $SUV_{max}$ was 2.23 based on the ROC curve. There was a significant correlation between the $SUV_{max}$ and the size of the cervical lymph nodes(Spearman r=0.353, p=0.048). Conclusion : FDG PET/CT images were more accurate than the CT/MRI images. In addition, the $SUV_{max}$ cut-off values were important for evaluating cervical the cervical nodes in the patients with SCC of the oral cavity and oropharynx.