• Progress in Medical Physics
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• v.34 no.3
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• pp.23-32
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• 2023

Purpose: In radiomics analysis, to evaluate features, and predict genetic characteristics and survival time, the pixel values of lesions depicted in computed tomography (CT) and magnetic resonance imaging (MRI) images are used. CT and MRI offer three-dimensional images, thus producing three-dimensional features (Features_3d) as output. However, in reports, the superiority between Features_3d and two-dimensional features (Features_2d) is distinct. In this study, we aimed to investigate whether a difference exists in the prediction accuracy of radiomics analysis of lung cancer using Features_2d and Features_3d. Methods: A total of 38 cases of large cell carcinoma (LCC) and 40 cases of squamous cell carcinoma (SCC) were selected for this study. Two- and three-dimensional lesion segmentations were performed. A total of 774 features were obtained. Using least absolute shrinkage and selection operator regression, seven Features_2d and six Features_3d were obtained. Results: Linear discriminant analysis revealed that the sensitivities of Features_2d and Features_3d to LCC were 86.8% and 89.5%, respectively. The coefficients of determination through multiple regression analysis and the areas under the receiver operating characteristic curve (AUC) were 0.68 and 0.70 and 0.93 and 0.94, respectively. The P-value of the estimated AUC was 0.87. Conclusions: No difference was found in the prediction accuracy for LCC and SCC between Features_2d and Features_3d.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.126-126
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• 2009

X-ray high-voltage generator is the most important part that can decide the radiation exposure dose affecting a patient or operator according to the characteristic. If decrease of X-ray radiation exposure dose and output characteristic of high-voltage generator is unstable, a patient or operator must be exposed to more radiation. This study measures and analyzes the exposure dose reproducibility and output characteristic according to a change of tube current on the various rectification methods of diagnostic X-ray equipment. It can find that quality bastardize and output is increased if voltage of X-ray tube is increased. Exposure dose reproducibility according to output of X-ray equipment is extremely excellent in inverter type, and is stable in order of following three-phase, a single-phase and condenser method. This study can find that the reply incidence of high-voltage generator is generated due to difference in rectification method, noise occurs in X-ray due to that, quality of an image is decreased due to that, and medical diagnosis can be failed due to that.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.13 no.2
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• pp.85-95
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• 2007

Purpose: The purpose of this study was to investigate the prevalence and affecting factors of work-related musculoskeletal disorder (WRMSD) among the directory assistance operators. Methods: One hundred eighty-five female subjects who worked more than one year as directory assistance operators in a telecommunication company were surveyed with self-administered questionnaires. Subjects were divided into disorder and control group by the NIOSH criterion about WRMSD, and then analyzed. Results: One hundred seventy two subjects (93%) had upper extremity symptoms and seventy subjects (37.8%) were WRMSD. the frequency order of the disorder area was the shoulder 60(32.4%), the neck 37(20.0%), the wrist 20(10.8%), the finger 20(10.8%) and the elbow 5(2.7%). It was found that the difference factors of the WRMSD group were education level (p<0.01), stress from the customers (p<0.01), satisfaction about monitor (p<0.05), temperature (p<0.05), noise (p<0.01), ventilation (p<0.001), working time (p<0.05), and recess (p<0.001). Conclusion: Improving working condition and education for the workers to control the stress are necessary to decrease the WRMSD for the directory assistance operators.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.496-502
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• 2005

This study was performed to compare the effect of external ultrasound assisted PAL(power assisted liposuction) with that of PAL alone. We performed 17 cases of liposuction from January 2003 to June 2003. For comparing both systems, we treated the right side(study group) with external ultrasound assisted PAL and the left side(control group) with PAL alone. To evaluate the difference in results between two groups, we surveyed three objective and four subjective items. Objectives were categorized as "Reduction rate of postoperative swelling", "Efficiency of suction" and "Histologic finding of aspirated fat tissue". Subjectives were also filed as "Degree of postoperative bruising", "Cannula resistance that operator felt", "Degree of postoperative pain" and "Patient's satisfaction". We assessed by questionnaire three times at 1day, 7 days and 30 days after operation. There were statistically significant differences in two of the subjective items; "Degree of postoperative pain at postoperative 1 day" and "Cannula resistance that operator felt". This study concludes that external ultrasound PAL is more effective high mobility of fat tissue and low tension of surrounding tissue. External ultrasound PAL will be more useful in case of large volume liposuction and revision procedures.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.397-403
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• 2016

Generally, an electrical distribution configuration is a radial system with one-way current in a distribution management system (DMS). All feeders in a DMS have tie-switches to make radial system. Sometimes, DMS should change a tie-switch for operation. In that case, the tie-switch has to be closed first; then a switch is opened as another tie-switch in order to prevent blackout for customers. At the moment when the tie-switch is closed, distribution system is operated in a loop state, not radial. Before the loop operation, DMS operator has to check any expected events for stable distribution system operation; and the most important event is a mis-operation of a protection relay. In addition, DMS operator should check voltage profile violation but a calculation method of section voltages had not been used. Thus, this paper proposes a calculation method of section voltages at a loop operation in a DMS. The proposed calculation algorithm is verified by Matlap Simulink.

• Kyungpook Mathematical Journal
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• v.57 no.4
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• pp.631-640
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• 2017

The aim of this paper is to introduce the binomial sequence spaces $b_0^{r,s}(\nabla)$, $b_c^{r,s}(\nabla)$ and $b_{\infty}^{r,s}(\nabla)$ by combining the binomial transformation and difference operator. We prove that these spaces are linearly isomorphic to the spaces $c_0$, c and ${\ell}_{\infty}$, respectively. Furthermore, we compute the Schauder bases and the ${\alpha}-$, ${\beta}-$ and ${\gamma}-duals$ of these sequence spaces.

• Journal of applied mathematics & informatics
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• v.33 no.5_6
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• pp.485-502
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• 2015

A computational method for solving singularly perturbed boundary value problem of differential equation with shift arguments of mixed type is presented. When shift arguments are sufficiently small (o(ε)), most of the existing method in the literature used Taylor's expansion to approximate the shift term. This procedure may lead to a bad approximation when the delay argument is of O(ε). The main idea for this work is to deal with constant shift arguments, which are independent of ε. In the present method, we construct the formally asymptotic solution of the problem using the method of composite expansion. The reduced problem is solved numerically by using operator compact implicit method, and the second problem is solved analytically. Error estimate is derived by using the maximum norm. Numerical examples are provided to support the theoretical results and to show the efficiency of the proposed method.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.22-27
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• 2006

This paper describes the development of the stream-tube based dispersion model for modeling contaminant transport in open channels. The operator-splitting technique is employed to separate the 2D contaminant transport equation into the pure advection and pure dispersion equations. Then the total variation diminishing (TVD) schemes are combined with the second-order Lax-Wendroff and third-order QUICKEST explicit finite difference schemes respectively to solve the pure advection equation in order to prevent the occurrence of numerical oscillations. Due to various limiters owning different features, the numerical tests for 1D pure advection and 2D dispersion are conducted to evaluate the performance of different TVD schemes firstly, then the TVD schemes are applied to experimental data for simulating the 2D mixing in a straight trapezoidal channel to test the model capability. Both the numerical tests and model application show that the TVD schemes are very competent for solving the advection-dominated transport problems.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.1
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• pp.61-74
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• 2014

This paper presents accurate and efficient numerical methods for calculating the sensitivities of two-asset European options, the Greeks. The Greeks are important financial instruments in management of economic value at risk due to changing market conditions. The option pricing model is based on the Black-Scholes partial differential equation. The model is discretized by using a finite difference method and resulting discrete equations are solved by means of an operator splitting method. For Delta, Gamma, and Theta, we investigate the effect of high-order discretizations. For Rho and Vega, we develop an accurate and robust automatic algorithm for finding an optimal value. A cash-or-nothing option is taken to demonstrate the performance of the proposed algorithm for calculating the Greeks. The results show that the new treatment gives automatic and robust calculations for the Greeks.

• Journal of the Korean Mathematical Society
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• v.47 no.1
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• pp.135-163
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• 2010

Motivated by [Science in China (Ser. A Mathematics) 36 (2006), no. 7, 721?732], this article deals with the following discrete type BVP $\LARGE\left\{{{\;{\Delta}[{\phi}({\Delta}x(n))]\;+\;f(n,\;x(n\;+\;1),{\Delta}x(n),{\Delta}x(n + 1))\;=\;0,\;n\;{\in}\;[0,N],}}\\{\;{x(0)-{\sum}^m_{i=1}{\alpha}_ix(n_i) = A,}}\\{\;{x(N+2)-\;{\sum}^m_{i=1}{\beta}_ix(n_i)\;=\;B.}}\right.$ The sufficient conditions to guarantee the existence of at least three positive solutions of the above multi-point boundary value problem are established by using a new fixed point theorem obtained in [5]. An example is presented to illustrate the main result. It is the purpose of this paper to show that the approach to get positive solutions of BVPs by using multifixed-point theorems can be extended to treat nonhomogeneous BVPs. The emphasis is put on the nonlinear term f involved with the first order delta operator ${\Delta}$x(n).