• Steel and Composite Structures
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• 제43권1호
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• pp.1-17
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• 2022

The free and forced nonlinear dynamic behaviors of Porous Functionally Graded Material (PFGM) plates are examined by means of a High-Order Implicit Algorithm (HOIA). The formulation is developed using the Third-order Shear Deformation Theory (TSDT). Unlike previous works, the formulation is written without resorting to any homogenization technique neither rule of mixture nor considering FGM as a laminated composite, and the distribution of the porosity is assumed to be gradually variable through the thickness of the PFGM plates. Using the Hamilton principle, we establish the governing equations of motion. The Finite Element Method (FEM) is used to compute approximations of the resulting equations; FEM is adopted using a four-node quadrilateral finite element with seven Degrees Of Freedom (DOF) per node. Nonlinear equations are solved by a HOIA. The accuracy and the performance of the proposed approach are verified by presenting comparisons with literature results for vibration natural frequencies and dynamic response of PFGM plates under external loading. The influences of porosity volume fraction, porosity distribution, slenderness ratio and other parameters on the vibrations of PFGM plate are explored. The results demonstrate the significant impact of different physical and geometrical parameters on the vibration behavior of the PFGM plate.

• Steel and Composite Structures
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• 제45권3호
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• pp.331-348
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• 2022

The main goal of this article is to develop the finite element formulation based on the nonlocal strain gradient and the refined higher-order deformation theory employing a new function f(z) to investigate the static bending and free vibration of functionally graded porous (FGP) nanobeams. The proposed model considers the simultaneous effects of two parameters: nonlocal and strain gradient coefficients. The nanobeam is made by FGP material that exists in un-even and logarithmic-uneven distribution. The governing equation of the nanobeam is established based on Hamilton's principle. The authors use a 2-node beam element, each node with 8 degrees of freedom (DOFs) approximated by the C¹ and C² continuous Hermit functions to obtain the elemental stiffness matrix and mass matrix. The accuracy of the proposed model is tested by comparison with the results of reputable published works. From here, the influences of the parameters: nonlocal elasticity, strain gradient, porosity, and boundary conditions are studied.

• 대한두경부종양학회지
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• 제20권1호
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• pp.13-18
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• 2004

Objectives: Cancer lethality is usually the result of local invasion and metastasis of neoplastic cell from the primary tumor. Because of their ability to degrade extracellular matrix components, matrix metalloproteinases (MMPs) and basic fibroblast growth factor (bFGF) have been implicated in the breakdown of basement membrane and underlying stroma, thereby facilitating tumor growth and invasion. It has been well established that MMPs and bFGF expression correlate with cervical lymph node metastasis, but studies on expression in the metastatic cervical lymph node itself are not enough. We have analyzed matrix metalloproteinases (MMPs) and basic fibroblast growth factor (bFGF) in squamous cell carcinoma of the head and neck and metastatic cervical lymph node, and evaluated their relationship and clinicophathologic significance. Material and Methods: 20 cases of squamous cell carcinoma of the head and neck were entered on the study of immunohistochemical stains for MMP-9 and bFGF in the obtained tissue from primary tumor and metastatic cervical lymph node. We analyzed the relationship between MMP-9, bFGF expression of the primary tumor and metastatic node with age, sex, T-stage, N-stage, histologic grade, pathologic stage and disease free survival. Results: Expression of MMP-9 and bFGF in cancer cell and metastatic lymph node was higher than that in normal cell and lymph node. According to histologic differentiation, expression of MMP-9 of the metastatic cervical lymph node was higher than primary tumor. Considering to other clinicopathologic factor, no statistical significance was seen in MMP-9 and bFGF. Conclusion: We found that expression of MMP-9 is higher in the metastatic lymph node than primary tumor in the poorly differentiated squamous cell carcinoma. But we don't find out the statistical significance in relation between bFGF and clinical factors. So we guess that some different mechanism of MMP-9 and bFGF in Head & Neck squamous cell carcinoma exist. Further studies will be necessary to establish their pathogenesis in the Head and Neck cancer.

• Advances in materials Research
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• 제12권1호
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• pp.43-65
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• 2023

Free vibration analysis of power law and sigmoidal sandwich plates made up of functionally graded materials (FGMs) has been carried out using finite element based higher-order zigzag theory. The present model satisfies all-important conditions such as transverse shear stress-free conditions at the plate's top and bottom surface along with continuity condition for transverse stresses at the interface. A Nine-noded C0 finite element having eleven degrees of freedom per node is used during the study. The present model is free from the requirement of any penalty function or post-processing technique and hence is computationally efficient. The present model's effectiveness is demonstrated by comparing the present results with available results in the literature. Several new results have been proposed in the present work, which will serve as a benchmark for future works. It has been observed that the material variation law, power-law exponent, skew angle, and boundary condition of the plate widely determines the free vibration behavior of sandwich functionally graded (FG) plate.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권5호
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• pp.209-216
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• 2013

전통적인 사회관계망 분석에 있어서 각 노드의 매개 중심도는 메시지 전달 측면에서의 각 노드들의 상대적인 중요도를 파악하는 척도로 오랫동안 사용되어 왔다. 하지만, 매개 중심도를 산출하기 위한 계산 복잡도가 높기 때문에 노드의 수와 간선의 수가 매우 많은 대규모 사회관계망에서는 각 노드의 매개 중심도를 산출하기가 어렵다. 본 논문에서는 각 노드들마다 자신의 지역정보, 즉 이웃노드들이 지닌 각각의 이웃노드 정보를 활용하여 구성가능한 확장 자아 네트워크(Expanded Ego Network)를 새롭게 정의하고 이러한 네트워크를 기반으로 확장 자아 매개 중심도(Expanded Ego Betweenness Centrality)를 정의한다. 일반적인 사회관계망의 특성인 척도 없는 네트워크(Scale-free Network)를 생성할 수 있는 Barab$\acute{a}$si-Albert 네트워크 모델을 사용한 실험을 통하여 제안한 확장 자아 매개 중심도의 각 노드별 순위는 기존의 전통적인 방식으로 산출한 매개 중심도의 각 노드별 순위와 거의 일치함을 보인다.

• 대한두개안면성형외과학회지
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• 제18권1호
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• pp.37-43
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• 2017

Background: Skin cancer is the most common type of cancer. Of the 4 million skin lesions excised annually worldwide, approximately 2 million are considered cancerous. In this study, we aimed to describe a regional experience with skin cancers treated by a single senior surgeon and to provide a treatment algorithm. Methods: The medical records of 176 patients with head and neck non-melanocytic skin cancer (NMSC) who were treated by a single surgeon at our institution between January 2010 and May 2016 were retrospectively reviewed, and their data (age, sex, pathological type, tumor location/size, treatment modality) were analyzed. Patients with cutaneous squamous cell carcinoma (cSCC) who were classified as a high-risk group for nodal metastasis underwent sentinel node mapping according to the National Comprehensive Cancer Network guidelines. Results: Among the patients with NMSC who were treated during this period, basal cell carcinoma (BCC; n=102, 57.9%) was the most common pathological type, followed by cSCC (n=66, 37.5%). Most lesions were treated by complete excision, with tumor-free surgical margins determined via frozen section pathology. Thirty-one patients with high-metastasis-risk cSCC underwent sentinel node mapping, and 17 (54.8%) exhibited radiologically positive sentinel nodes. Although these nodes were pathologically negative for metastasis, 2 patients (6.5%) later developed lymph node metastases. Conclusion: In our experience, BCC treatment should comprise wide excision with tumor-free surgical margins and proper reconstruction. In contrast, patients with cSCC should undergo lymphoscintigraphy, as nodal metastases are a possibility. Proper diagnosis and treatment could reduce the undesirably high morbidity and mortality rates.

• Asian Pacific Journal of Cancer Prevention
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• 제14권5호
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• pp.2851-2857
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• 2013

Objective: REPS2 plays important roles in inhibiting cell proliferation, migration and in inducing apoptosis of cancer cells, now being identified as a useful biomarker for favorable prognosis in prostate and breast cancers. The purpose of this study was to assess REPS2 expression and to explore its role in esophageal squamous cell carcinoma (ESCC). Methods: Protein expression of REPS2 in ESCCs and adjacent non-cancerous tissues from 120 patients was analyzed by immunohistochemistry and correlated with clinicopathological parameters and patient outcome. Additionally, thirty paired ESCC tissues and four ESCC cell lines and one normal human esophageal epithelial cell line were evaluated for REPS2 mRNA and protein expression levels by quantitative RT-PCR and Western blotting. Results: REPS2 mRNA and protein expression levels were down-regulated in ESCC tissues and cell lines. Low protein levels were significantly associated with primary tumour, TNM stage, lymph node metastasis and recurrence (all, P < 0.05). Survival analysis demonstrated that decreased REPS2 expression was significantly associated with shorter overall survival and disease-free survival (both, P < 0.001), especially in early stage ESCC patients. When REPS2 expression and lymph node metastasis status were combined, patients with low REPS2 expression/lymph node (+) had both poorer overall and disease-free survival than others (both, P < 0.001). Cox multivariate regression analysis further revealed REPS2 to be an independent prognostic factor for ESCC patients. Conclusions: Our findings demonstrate that downregulation of REPS2 may contribute to malignant progression of ESCC and represent a novel prognostic marker and a potential therapeutic target for ESCC patients.

• 한국항공우주학회지
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• 제39권8호
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• pp.750-757
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• 2011

센서 네트워크는 보통 넓은 지역에 조밀하게 센서 노드들이 분포되어 있는 형태로 구성된다. 이런 센서 노드들은 광활한 지역에 분포되는 관계로 초기에 헬기 등 기타 항공기를 이용해서 뿌려지는 것이 일반적이다. 각 센서 노드들은 특정 임무를 수행하며 획득된 정보를 자신의 위치 정보와 함께 최종 사용자에게 전달되는 형태로 운용된다. 여기서 노드들의 위치 정보가 필요하다. 본 논문은 센서 네트워크에서 헬기의 비콘 신호를 이용하여 센서 노드 사이의 거리정보를 필요로 하지 않는 알고리즘을 제안하였다. 센서 노드들은 위치를 계산하기 위해 헬기가 보내주는 주기적인 비콘 신호를 수신한다. 비콘 신호를 메모리에 저장하고 있다가 조건에 만족하는 다른 비콘 신호가 수신되면 이를 통해 자신의 위치를 추측한다. 이를 위해 본 논문에서는 기하학적 성질(현의 수직이등분)을 이용하였다. 기존에 존재하는 range-free 방식의 알고리즘과 비교 분석을 통해 제안하는 알고리즘의 정밀성을 입증하였다.

• 디지털융복합연구
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• 제13권7호
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• pp.207-212
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• 2015

사물 인터넷을 구성하는 센서 네트워크는 주변 환경의 여러 정보들을 효율적으로 수집하여 앵커 노드로 보내기 위해서 최적의 경로를 선택하여 센서 간의 통신비용 및 수명 연장을 위해 많은 연구가 필요하다. 센서 네트워크에서 센서노드는 저전력, 저용량을 갖는 확장 장치이다. 이들 노드들 간의 데이터 전송을 위한 라우팅 방법을 위해 인접한 지역에 있는 앵커와 노드간의 연결은 적은 오류로 비교적 정확해야 한다. 이러한 지역화를 위한 기존의 방법 중 CA(Centroid Algorithm)는 자주 사용하는 방법이기는 하지만 오류가 자주 일어난다. 본 논문에서는 이러한 오류 발생의 문제점을 최소화하기 위해 Radical Line을 기반으로 한 센서 노드 간에 range-free 지역화 방법을 제안한다.

• 한국멀티미디어학회논문지
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• 제25권10호
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• pp.1404-1415
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• 2022

The 2-dimensional arrangement method of nodes has been used in most of RF (Radio Frequency) based communication network simulations. However, this method is not useful for the an none-obstacle 3-dimensional space networks in which the propagation delay speed in communication is very slow and, moreover, the values of performance factors such as the communication speed and the error rate change on the depth of node. Such a typical example is an underwater communication network. The 2-dimensional arrangement method is also not useful for the RF based network like some WSNs (Wireless Sensor Networks), IBSs (Intelligent Building Systems), or smart homes, in which the distance between nodes is short or some of nodes can be arranged overlapping with their different heights in similar planar location. In such cases, the 2-dimensional network simulation results are highly inaccurate and unbelievable so that they lead to user's erroneous predictions and judgments. For these reasons, in this paper, we propose a method to place uniformly and randomly communication nodes in 3-dimensional network space, making the wireless link with neighbor node possible. In this method, based on the communication rage of the node, blocks are generated to construct the 3-dimensional network and a node per one block is generated and placed within a block area. In this paper, we also introduce an algorithm based on this method and we show the performance results and evaluations on the average time in a node generation and arrangement, and the arrangement time and scatter-plotted visualization time of all nodes according to the number of them. In addition, comparison with previous studies is conducted. As a result of evaluating the performance of the algorithm, it was found that the processing time of the algorithm was proportional to the number of nodes to be created, and the average generation time of one node was between 0.238 and 0.28 us. ultimately, There is no problem even if a simulation network with a large number of nodes is created, so it can be sufficiently introduced at the time of simulation.