• 국제물리치료학회지
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• 제7권2호
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• pp.1031-1036
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• 2016

c-Fos is known to related to synaptic plasticity and apoptosis in damage from ischemia or external injury. The purpose of this study was to investigate whether needle electrode electrical stimulation(NEES) is effective in increasing the number of c-Fos response cells and c-Fos expression in striatum after global ischemia in rats. There were no treatment and occlusion in the control group, global ischemia(GI) group were no treatment after carotid artery occlusion, and needle electrode electrical stimulation(NEES) group were treated with NEES after GI induced. The number of striatum c-Fos response cells and c-Fos protein expression significantly decreased in the NEES group compared to the GI group after 12, 24, 48 hours. The results of the present study suggest that NEES is ineffective in improving global ischemia in rats and may also be ineffective in the globally ischemic human brain.

• 소성∙가공
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• 제12권2호
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• pp.88-93
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• 2003

Several alloy bearing steels have been starting to replace for conventional high carbon and high chromium bearing steel since 1980. In this paper the global bearing developing trends were summarized in several important aspects- developments in alloy bearing steels for improved service life, development of inclusion rating method in bearing steel and developments in bearing service life testing.

• 소성∙가공
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• 제6권5호
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• pp.416-424
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• 1997

In the present study, a contact search and check algorithm for general tool surface described by triangular FE patch is proposed. To improve numerical stability, SEAM element using the linear Coons interpolation has been used. To check the proposed algorithm, both clover cup and L-shape cup deep drawing processes are calculated. The computed results shows that the proposed contact algorithm can be successfully applied for sheet metal forming processes with general shaped tools.

• 소성∙가공
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• 제16권7호
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• pp.538-548
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• 2007

In this paper, a novel approach which enables rapid die surface modification for sheet metal forming process is proposed. In this method an implicit surface which interpolates a given set of control points and displacement constraints is generated to compute the displacements at arbitrary points located on die surface. The proposed method does not depend on the underlying surface representation type and is affected neither by its complexity nor by its quality. In addition, the domain decomposition method is introduced in order to treat large surface model. The global domain of interest is divided into smaller domains where the problem can be solved locally. And then the local solutions are combined together to obtain a global solution. In order to verify the validity and effectiveness of the proposed method, various surface modifications are carried out fur three kinds of die surface model including polygonal surface composed of triangular and rectangular meshes, polynomial surface and NURBS surface.

• 국제물리치료학회지
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• 제11권3호
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• pp.2140-2146
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• 2020

Background: Stroke patients exhibit arm global synkinesis (GS), involuntary movement due to muscle weakness and irregular muscle tension. But currently there are few studies examined the effects of GS on activates of daily living in stroke patients. Objectives: To investigate the effects the effects of task-oriented bilateral movements, which promote brain plasticity and are based on neurological theory, using the unaffected arm and the affected arm. Design: Quasi-randomized trial. Methods: Twenty stroke patients were randomly assigned to experimental group I (n=10) and experimental group II (n=10). Before the intervention, arm GS was measured using surface electromyography, and the Motor Activity Log evaluated the quantitative and qualitative uses of the affected arm in daily life. The same items were measured four weeks later. Results: The changes in the GS of the arm of experimental group I showed statistically significant differences only in bending motions (P<.05). Both groups showed statistically significant differences in the amount of use (AOU) and the quality of movement (QOM) scores (P<.01). Comparing the groups, statistically significant differences in GS appeared during bending motions (P<.05), and in the AOU (P<.01) and the QOM scores (P<.05). Conclusion: The intervention in GS reduced the abnormal muscle tension of the affected side by increasing the use of the ipsilateral motor pathway, indicating its effectiveness in improving upper limb functions with smooth contraction and relaxation of the muscles.

• Structural Engineering and Mechanics
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• 제58권4호
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• pp.731-743
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• 2016

Plastic behaviors, based on the von Mises yield criterion, of circular discs containing a purely elastic, circular inclusion under uniform temperature loading are studied with the finite element analysis. Temperature-dependent mechanical properties are considered for the matrix material only. In addition to analyzing the plane stress and plane strain disc, a 3D thin disc and cylinder are also analyzed to compare the plane problems. We determined the elastic irreversible temperature and global plastic collapse temperature by the finite element calculations for the plane and 3D problem. In addition to the global plastic collapse, for the elastically hard case, the plane stress problem and 3D thin disc may exhibit a local plastic collapse, i.e. significant pile up along the thickness direction, near the inclusion-matrix interface. The pileup cannot be correctly modeled by the plane stress analysis. Furthermore, due to numerical difficulties originated from large deformation, only the lower bound of global plastic collapse temperature of the plane stress problem can be identified. Without considerations of temperature-dependent mechanical properties, the von Mises stress in the matrix would be largely overestimated.

• 소성∙가공
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• 제23권3호
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• pp.164-170
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• 2014

To predict the deformation and fracture during tube expansion using the finite element (FE) method, a material model is considered that incorporates the damage evolution due to the deformation. In the current study, a Rice-Tracey model was used as the damage model with inclusion of the hydrostatic stress term. Since OFHC Cu is not significantly affected by strain rate, a Hollomon flow stress model was used. The material parameters in each model were obtained by using an optimization method. The objective function was defined as the difference between the experimental measurements and FE simulation results. The parameters were determined by minimizing the objective function. To verify the validity of the FE modeling, cross-verification was conducted through a tube expansion test. The simulation results show reasonable agreement with the experiments. The design for a minimum diameter of expansion tube using the FE modeling was verified by a simplified tube expansion test and simulation results.

• 한국전산구조공학회논문집
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• 제14권4호
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• pp.435-444
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• 2001

대변형 탄소성 프레임의 해석은 운동학적, 재질적, 수치해법상으로 매우 복잡하여 정확하고 효율적인 요소나 알고리즘이 부족하다. 본 논문에서는 3차원 보요소에 대하여 봉이론으로부터 유한요소를 만들고 소성을 적용하기 위하여 Cauchy응력과 공학적변형률을 구성방정식에 적용하는 방법으로 객관화된 증분해법에 의한 보요소를 제안하였다. 특히 항복조건의 만족을 위하여 정확하고도 효율적인 소성방정식의 적분법을 개발하고 적용하였으며 연속법과 일차원 탐색 등을 고려하여 광역수렴성과 2차 수렴속도를 갖는 수치해법을 개발하고 예제를 통하여 확인하였다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.5-5
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• 2017

Too little and too much water due to climatic events is a significant cause of global food insecurity. Crops are less productive under water-limited conditions and all major crops, with the exception of rice (Oryza sativa), die within a few days of complete submergence. To complement our studies on genes such as SUB1A, (an ERF-VII transcription factor that provides robust submergence tolerance) and AG1 (a TREHALOSE 6-P PHOSPHATASE that promotes establishment of young seedlings underwater), we have retooled INTACT (${\underline{I}}solation$ of ${\underline{N}}uclei$ ${\underline{TA}}gged$ in specific ${\underline{C}}ell$ ${\underline{T}}ypes$) and TRAP (${\underline{T}}ranslating$ ${\underline{R}}ibosome$ ${\underline{A}}ffinity$ ${\underline{P}}urification$) for rice. These technologies enable us to follow dynamics in chromatin, nuclear pre-mRNAs and ribosome-bound mRNAs in meristems and diverse cell types. With these technologies we can better interpret responses to stresses and reestablishment of homeostasis. These include stress acclimation strategies involving changes in metabolism and development, such as dynamics in suberin deposition in sub-epidermal layers of roots that limit water loss under drought and oxygen escape during waterlogging. Our new data uncover dynamic and reversible regulation at multiple levels of gene regulation and provide new insights into processes of stress resilience. Supported by US NSF-PGRP Plasticity (IOS-1238243), Secretome (IOS-1546879) and REU (DBI-146129) grants.

• 한국해양공학회지
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• 제25권2호
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• pp.134-144
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• 2011

In this paper, the global study trends for material behaviors are investigated regarding the static and dynamic hardenings and final fractures of marine structural steels. In particular, after reviewing all of the papers published at the 4th and 5th ICCGS (International Conference on Collision and Grounding of Ship), the used hardening and fracture properties are summarized, explicitly presenting the material properties. Although some studies have attempted to employ new plasticity and fracture models, it is obvious that most still employed an ideal hardening rule such as perfect plastic or linear hardening and a simple shear fracture criterion with an assumed value of failure strain. HSE (2001) presented pioneering study results regarding the temperature dependency of material strain hardening at various levels of temperature, but did not show strain rate hardening at intermediate or high strain rate ranges. Nemat-Nasser and Guo (2003) carried out fully coupled tests for DH-36 steel: strain hardening, strain rate hardening, and temperature hardening and softening at multiple steps of strain rates and temperatures. The main goal of this paper is to provide the theoretical background for strain and strain rate hardening. In addition, it presents the procedure and methodology needed to derive the material constants for the static hardening constitutive equations of Ludwik, Hollomon, Swift, and Ramberg-Osgood and for the dynamic hardening constitutive equations of power from Cowper-Symonds and Johnson-Cook.