• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 춘계학술대회논문집
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• pp.145-155
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• 1996

The extrusion velocity of billet through a die and the shapes of the die are the important factors in the metal forming process of the extrusion of billet. in recent years, the life cycle of products is goingfaster. Although the former finite element method was capable of yielding a detailed analysis, it requires lots of time and extensive coding effort. Then, some simple devices were developed and based on upper bound method. For this purpose , a kinematically admiasible velocity field is formulated for extrusion of cylinders with arbitrary cross section and die profile on their outer surfaces by using a modified upper bound approach, which configures simulataneous extruding speeds in three directions . Also, In order to display mesh of the cold forward extrusion process using the approach , the automatic three-dimentional mesh generation produced by the approach coupled finite element method with upper bound method.

• 한국산업정보학회논문지
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• 제17권6호
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• pp.41-50
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• 2012

This paper presents a new sequence alignment method using the divide approach, which solves the problem by decomposing sequence alignment into several sub-alignments with respect to exact matching subsequences. Exact matching subsequences in the proposed method are bounded on the generalized suffix tree of two sequences, such as protein domain length more than 7 and less than 7. Experiment results show that protein sequence pairs chosen in PFAM database can be aligned using this method. In addition, this method reduces the time about 15% and space of the conventional dynamic programming approach. And the sequences were classified with 94% of accuracy.

• 대한조선학회논문집
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• 제43권6호
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• pp.683-692
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• 2006

The BEM, known as solving boundary value problems, could have some advantages In solving domain problems which are mostly solved by FEM and FDM. Lately, in the elastic-plastic nonlinear problems, BEM could provide the subdomain approach for the region where the plastic deformation could occur and the unknown nodal displacement of this region are added as the unknown of the boundary integral equation for this approach. In this paper, initial stress method was used to establish the formulation of such BEM approach. And a simple rectangular plate having a circular hole was analyzed to verify the suggested method and the result is compared with that from FEM. It is shown that the result of two methods are showing similar stress-strain curves at the root of perforated plate and furthermore the plastic deformation obtained by BEM shows more reasonable behavior than that of FEM.

• Journal of the Korean Statistical Society
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• 제19권1호
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• pp.1-14
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• 1990

This paper proposes an approach to the identification of trnasfer function models. A strategy for the identification of the model structure is based on R and S arrays constructed by the impulse response function of the model. Theoretical patterns of the arrays associated with the model are investigated, and the practical implementation method of the suggested approach is also discussed. Finally two published samples are employed to demonstrate the practicability of the approach.

• 한국CDE학회논문집
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• 제8권1호
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• pp.41-47
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• 2003

In this paper, a tetrahedral mesh generation algorithm which uses a grid based method for interior region and an advancing front method for outer surface region is proposed. In order to apply an advancing front method for outer region of an object, a new operator so called a hole operator has been developed to handle multiple shells. With this grid based approach in the interior region, more stable and uniform meshes can be constructed especially in the interior region.

• Archives of Plastic Surgery
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• 제35권2호
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• pp.152-158
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• 2008

Purpose: Mandibulotomy approach and mandible sparing approach are most common methods for oropharyngeal cancer surgery. Good surgical view and convenience of flap inset are advantages of mandibulotomy approach but deformity of mandible contour, postoperative malocclusion and radionecrosis are its limitations. To make up for the limitations, mandible sparing method is commonly performed, but limited surgical view and difficulties of flap inset are the weak points of this approach. The purpose of the study is to compare mandibulotomy and mandible sparing approaches in postoperative complications and progression of the treatment in oropharyngeal cancer operation and reconstruction. Methods: Single reconstructive microsurgeon operated for oropharyngeal cancer patients with different surgeons of head and neck department who prefer mandibulotomy and mandible sparing approach respectively, and we compared the frequency of postoperative complication, operation time, duration of hospitalization and recurrence rate between two different surgical approaches. Results: Mandibulotomy approach was used in 18 patients and mandible sparing approach was used in 15 patients. In mandibulotomy approach, there happened one case of teeth injury and one case of necrosis of skin and gingiva, but there happened no malocclusion and radionecrosis. In mandible sparing approach, there were 3 cases of fistula and 2 cases of infection which are significantly higher than mandibulotomy approach. There were no significant differences between early regional recurrence and duration of hospitalization. Conclusion: In this study we compared two different methods for the surgical approach in oropharyngeal cancer surgery. As mandible sparing approach has difficulties of limited surgical view, it can be used for the limited indications of anterior tongue and mouth floor cancer. Mandibulotomy approach has advantages of good surgical view and convenience of flap inset. In this method preservation of gingival tissue, watertight fashion suture, delicate osteotomy and plate fixation to maintain occlusion are the key points for the successful results.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.37-43
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• 2010

본 논문에서는 선형 구조물에 대해 성능함수법을 이용하여 신뢰성기반 위상 최적설계 기법을 개발하였다. 구조물을 라이즈너-민들린(Ressiner-Mindlin) 판 요소로 분할하였으며, 각 요소의 재료 물성치를 설계변수로 사용하였다. 설계변수와 임의변수의 효율적인 설계민감도를 구하기 위하여 연속체 역학에 기초한 해석기법 중 보조변수법(Adjont variable method)을 사용하였다. 또한 확률론적 제약조건을 평가하기 위해서 성능함수법(Performance measure approach)을 사용하였으며 변위 제약조건을 두어 위상 최적설계 문제를 구성하였다. 이 때 재료 물성치와 하중을 불확실 변수로 고려하였으며 수치적 예제를 통하여 본 논문에서 제안한 최적설계 방법론을 기존의 결정론적 방법, 안전계수법(Safety factor approach), 최악조건법(Worst case approach) 등과 비교하여 그 타당성을 검증하였다.

• 동의생리병리학회지
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• 제35권5호
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• pp.125-131
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• 2021

The scientific understanding of Korean medicine theory remains largely unknown, since there is a lack of proper methods to investigate its complex and unique characteristics. Here, we introduce a drug-centered approach, a novel method to investigate Korean medicine theory by analyzing the mechanisms of herbal medicines. This method can be effectively conducted by employing network pharmacology that can analyze the systems-level mechanisms of herbal medicines on a large scale. Firstly, we introduce the method of network pharmacology that are applied to analyze the mechanisms of herbal medicines in a step-by-step manner. Then, we show how the drug-centered approach employing network pharmacology can be applied to investigate Korean medicine theory by describing studies that identify the biological correlates of the cold-hot nature of herbs, spleen qi deficiency syndrome, or Sasang constitution. Finally, we discuss the limitations and future directions of the proposed approach in two aspects: The methods of network pharmacology for a drug-centered approach and the process of inferring Korean medicine theory through it. We believe that a drug-centered approach employing network pharmacology will provide an advanced scientific understanding of Korean medicine theory and contribute to its development by generating biologically plausible hypothesis.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권1호
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• pp.72-82
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• 2008

Various surgical approaches in the mandibular condyle fracture have been reported and many advantages of intraoral reduction were also introduced. But there are still controversies about surgical method of condylar fractures up to date. To establish the surgical approach protocol of condylar fracture, from May 2001 to December 2004, total 65 patients with 74 fractures of the mandibular condyle were reviewed during 2 years, retrospectively. All cases were classified according to the treatment considering factors, such as the level of fracture, degree and direction of displacement of fractured segment, patient’s age and gender, surgical approach methods, and their complications. Especially, advantages and surgical limitations of extraoral surgical approach, such as direct reduction and fixation via submandibular approach, Nam’s method, and endaural approach, were compared with those of intraoral surgical approach, such as direct intraoral reduction with transbuccal fixation or right angle driver system, and intraoral reinsertional approach after extraoral fixation of fractured fragment. The guidelines of surgical approach of condylar fracture based on our clilnical retrospective experiences and literature reviews can be suggested.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권2호
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• pp.494-510
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• 2024

Internet users are exposed to sophisticated cyberattacks that intrusion detection systems have difficulty detecting. Therefore, research is increasing on intrusion detection methods that use artificial intelligence technology for detecting novel cyberattacks. Unsupervised learning-based methods are being researched that learn only from normal data and detect abnormal behaviors by finding patterns. This study developed an anomaly-detection method based on unsupervised machines and deep learning for a network intrusion detection system (NIDS). We present a hybrid anomaly detection approach based on unsupervised learning techniques using the autoencoder (AE), Isolation Forest (IF), and Local Outlier Factor (LOF) algorithms. An oversampling approach that increased the detection rate was also examined. A hybrid approach that combined deep learning algorithms and traditional machine learning algorithms was highly effective in setting the thresholds for anomalies without subjective human judgment. It achieved precision and recall rates respectively of 88.2% and 92.8% when combining two AEs, IF, and LOF while using an oversampling approach to learn more unknown normal data improved the detection accuracy. This approach achieved precision and recall rates respectively of 88.2% and 94.6%, further improving the detection accuracy compared with the hybrid method. Therefore, in NIDS the proposed approach provides high reliability for detecting cyberattacks.