• 대한기계학회논문집B
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• 제32권10호
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• pp.754-760
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• 2008

Computation of moving interface by the level set method typically requires the reinitialization of level set function. An inaccurate estimation of level set function $\phi$ results in incorrect free-surface capturing and thus errors such as mass gain/loss. Therefore, an accurate and robust reinitialization process is essential to the simulation of free-surface flows. In the present paper, we pursue further development of the reinitialization process, which evaluates level set function directly using a normal vector on the interface without solving there-distancing equation of hyperbolic type. The Taylor-Galerkin approximation and P1P1 splitting/SUPG (Streamline Upwind Petrov-Galerkin) FEM are adopted to discretize advection equation of the level set function and the incompressible Navier-Stokes equation, respectively. Advection equation and re-initialization process of free surface capturing are validated with benchmark problems, i.e., a broken dam flow and timereversed single vortex flow. The simulation results are in good agreement with the existing results.

• Archives of Plastic Surgery
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• 제50권3호
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• pp.264-273
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• 2023

The medial sural artery perforator (MSAP) flap is a versatile fasciocutaneous flap, and yet is less commonly utilized than other free flaps in microvascular reconstructions of the head and neck. The aim is to conduct a high-quality Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA)- and Assessment of Multiple Systematic Reviews 2 (AMSTAR 2)-compliant systematic review comparing the use of the MSAP flap to other microvascular free flaps in the head and neck. Medline, Embase, and Web of Science databases were searched to identify all original comparative studies comparing patients undergoing head and neck reconstruction with an MSAP flap to the radial forearm free flap (RFFF) or anterolateral thigh (ALT) flap from inception to February 2021. Outcome studied were the recipient-site and donor-site morbidities as well as speech and swallow function. A total of 473 articles were identified from title and abstract review. Four studies met the inclusion criteria. Compared with the RFFF and the ALT flaps, the MSAP flap had more recipient-site complications (6.0 vs 10.4%) but less donor-site complications (20.2 vs 7.8%). The MSAP flap demonstrated better overall donor-site appearance and function than the RFFF and ALT flaps (p = 0.0006) but no statistical difference in speech and swallowing function following reconstruction (p = 0.28). Although higher quality studies reviewing the use of the MSAP flap to other free flaps are needed, the MSAP flap provides a viable and effective reconstructive option and should be strongly considered for reconstruction of head and neck defects.

• 대한통합의학회지
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• 제8권2호
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• pp.53-61
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• 2020

Purpose : We investigated the correlation between body composition and lung function in healthy adults. Methods : This study included 204 healthy adults in whom all measurements were obtained once, and all data were analyzed using the SPSS software for Windows, version 22.0. Pearson's correlation analysis was performed to determine the correlation between body composition (represented by the total body water, protein mass, soft lean mass, mineral mass, basal metabolic rate, fat-free mass, skeletal muscle mass, and body fat percentage) and lung function (represented by the forced vital capacity [FVC], forced expiratory volume in 1 second [FEV₁], the FEV₁/FVC ratio, maximum voluntary ventilation [MVV], maximum expiratory pressure [MEP], and the maximum inspiratory pressure [MIP]). All measurements were obtained by two investigators to improve reliability. A significance level of α=.05 was used to verify statistical significance. Results : Among the lung function measurements obtained in both men and women, the FVC, FEV₁, MVV, and MIP were positively correlated with the total body water, protein mass, soft lean mass, mineral mass, basal metabolic rate, fat-free mass, and skeletal muscle mass in men (p<.05). The FEV₁/FVC ratio was negatively correlated with the total body water, soft lean mass, mineral mass, basal metabolic rate, fat-free mass and the body fat percentage (p<.05). Notably, the FVC, FEV₁, and MVV were positively correlated with the total body water, protein mass, soft lean mass, mineral mass, basal metabolic rate, fat-free mass, and skeletal muscle mass in women (p<.05). Conclusion : This study showed a significant correlation between body composition and lung function in healthy adults. In combination with future studies on lung function, our results can provide objective evidence regarding the importance of prevention of lung disease, and our data can be utilized in rehabilitation programs for patients with respiratory diseases.

• 대한수학회지
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• 제51권6호
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• pp.1291-1304
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• 2014

In 2005 Kadiri proved that the Riemann zeta function ${\zeta}(s)$ does not vanish in the region $$Re(s){\geq}1-\frac{1}{R_0\;{\log}\;{\mid}Im(s){\mid}},\;{\mid}Im(s){\mid}{\geq}2$$ with $R_0=5.69693$. In this paper we will show that $R_0$ can be taken $R_0=5.68371$ using Kadiri's method together with Platt's numerical verification of Riemann Hypothesis.

• Structural Engineering and Mechanics
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• 제57권2호
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• pp.281-294
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• 2016

The paper is devoted to study a mesh-free analysis method of structural elements of engineering structures based on B-spline Wavelet Basis Function. First, by employing the moving-least square method and the weighted residual method to solve the structural displacement field, the control equations and the stiffness equations are obtained. And then constructs the displacement field of the structure by using the m-order B-spline wavelet basis function as a weight function. In the end, the paper selects the plane beam structure and the structure with opening hole to carry out numerical analysis of deformation and stress. The Finite Element Method calculation results are compared with the results of the method proposed, and the calculation results of the relative error norm is compared with Gauss weight function as weight function. Therefore, the clarification verified the validity and accuracy of the proposed method.

• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.51-61
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• 2022

This paper presents a model-free system based on a framework of a backstepping sliding mode control (BSMC) with a radial basis function neural network (RBFNN) and adaptive mechanism for electro-hydraulic systems (EHSs). First, an EHS mathematical model was dedicatedly derived to understand the system behavior. Based on the system structure, BSMC was employed to satisfy the output performance. Due to the highly nonlinear characteristics and the presence of parametric uncertainties, a model-free approximator based on an RBFNN was developed to compensate for the EHS dynamics, thus addressing the difficulty in the requirement of system information. Adaptive laws based on the actor-critic neural network (ACNN) were implemented to suppress the existing error in the approximation and satisfy system qualification. The stability of the closed-loop system was theoretically proven by the Lyapunov function. To evaluate the effectiveness of the proposed algorithm, proportional-integrated-derivative (PID) and improved PID with ACNN (ACPID), which are considered two complete model-free methods, and adaptive backstepping sliding mode control, considered an ideal model-based method with the same adaptive laws, were used as two benchmark control strategies in a comparative simulation. The simulated results validated the superiority of the proposed algorithm in achieving nearly the same performance as the ideal adaptive BSMC.

• 한국경제지리학회지
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• 제5권2호
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• pp.249-275
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• 2002

선진 외국인 투자기업 유치를 통해 수출진흥, 고용증대, 기술향상의 추구와 지역사회개발촉진을 위해 설치된 익산자유무역지대는 1980년대 중반 이후 외국인 투자업체, 수출, 고용이 감소되면서 그 기능은 크게 약화되어 수출자유지대로서의 존재가치가 무의미한 실정이다 익산자유무역지대의 기능의 약화 요인은 적지선정에 있어 수출자유지대의 기능 활성화를 위해 필요한 입지요인과 지역이 지니고 있는 입지여건을 고려하지 않고 선정됨으로서 설립초기부터 입지상의 문제가 내재되어 있었다. 또한 현재의 노동집약적인 지역산업구조는 저임금에 기초한 노동집약적 업체의 집적지라는 부정적인 인식으로 작용하여 기술집약적인 첨단산업으로의 자유무역지대의 산업구조 개편에 어려움을 주고 있다. 그리고 정책의 일관성 부족으로 인한 협소한 부지면적과 부족한 확장공간은 기업의 집적효과와 규모의 경제를 약화시켰으며, 열악한 입지여건을 개선시키고 지역의 동태적 비교우위를 창출하려는 정부의 정책과 의지부족은 외국인 투자기업의 투자 유인력을 약화시키고 있다.

• Archives of Reconstructive Microsurgery
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• 제23권1호
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• pp.8-12
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• 2014

Purpose: The success rate of free flap operation has shown a recent increase. Especially for breast reconstructive patients, aesthetic results are considered a necessity. However, for patients who underwent reconstruction in parts of the body other than breast, for example, head and neck, lower and upper extremities, aesthetic considerations are underscored. Nowadays, however, aesthetic standpoint toward these patients is changing. Materials and Methods: We conducted a retrospective review of 8 patients who underwent secondary procedures after free flap surgery from March of 2011 to April of 2014. Results: Secondary refinement was a safe and less time-consuming technique for maximizing the function and aesthetic appearance for the patient. Conclusion: Appearance has become increasingly important with regard to function and quality of life. Therefore, for free flap reconstructive patients, secondary refinements may be considered in order to change the shape and contour. The secondary refinements are critical to the final result and must be a planned part of the entire reconstructive sequence.

• Geomechanics and Engineering
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• 제21권3호
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• pp.237-245
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• 2020

The process of evaporation from free water surface was simulated in a large scale environmental chamber under various controlled atmospheric conditions and also was modelled by a new mass transfer model. Six evaporation tests were conducted with increasing wind speed and air temperature in the environmental chamber, and hence the effect of atmosphere parameters on the evaporation process and the corresponding response of water were investigated. Furthermore, based on the experiment results, seven general types of mass transfer models were evaluated firstly, and then a new model consisted of wind speed function and air relative humidity function was proposed and validated. The results show that the free water evaporation is mainly affected by the atmospheric parameters and the evaporation rate increases with the increasing air temperature and wind speed. Both the air and soil temperatures are affected by the energy transformation during water evaporation. The new model can satisfactorily describe the evaporation process from free water surface under different atmospheric conditions.

• Interaction and multiscale mechanics
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• 제3권2호
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• pp.123-143
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• 2010

The essential idea of the element-free Galerkin method (EFG) is that moving least-squares (MLS) approximation are used for the trial and test functions with the variational principle (weak form). By using the weighted orthogonal basis function to construct the MLS interpolants, we derive the formulae for an improved element-free Galerkin (IEFG) method for solving three-dimensional problems in linear elasticity. There are fewer coefficients in improved moving least-squares (IMLS) approximation than in MLS approximation. Also fewer nodes are selected in the entire domain with the IEFG method than is the case with the conventional EFG method. In this paper, we selected a few example problems to demonstrate the applicability of the method.