• 전산구조공학
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• 제8권2호
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• pp.85-93
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• 1995

본 연구는 병렬전단벽 구조물의 변환부분의 효율적인 유한요소해석을 위한 보-변환요소 및 변환부분의 요소를 제시하고자 한다. 먼저 보-변환요소는 보요소와 벽체요소사이의 변형 및 힘의 구속조건을 근거로하여 보의 기본적인 거동을 동일하게 유지하면서 평면응력요소의 개념으로 대치된 유사보요소로 간주될 수 있으며, 이는 변환부분에서의 보요소와 벽체요소사이의 서로 다른 자유도에 기인한 변형의 부적합성을 합리적으로 해결해준다. 또한 보-변환요소와 직접 연결되는 변환부분의 요소는 보-변환요소의 경우와 동일한 구속조건이 적용됨으로써 변환부분에 대한 효율적인 요소분할방안을 제시해 준다. 이와 같이 본 연구에서 제시된 요소들은 기본적으로 병렬전단벽 구조물 뿐만아니라 보요소와 벽체요소의 상호작용이 고려되는 모든 구조물에 효율적으로 활용될 수 있다.

• 대한약리학회지
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• 제32권3호
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• pp.335-345
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• 1996

허혈/재관류 뇌손상에서 활성산소류의 역할이 중요시되고 있다. 본 연구에서는 모래쥐의 총경동맥을 묶었다 풀어줌으로써 실험적 허혈/재관류 손상을 유도하고 산화성 스트레스 발생 유무와 이러한 산화성 스트레스가 세포손상으로 연결되는지를 알아보고자 하였다. 해마는 뇌조직 중에서도 특히 산화성 스트레스에 취약한 부분이므로 해마에서 얻은 조직을 대뇌피질에서 얻은 조직과 비교분석하였다. 또한, 이들 부위에서 heat shock protein 70(HSP70)의 발현이 허혈/재관류 손상에 미치는 영향도 검색하고자 하였다. 허혈/재관류에 의한 산화성 스트레스의 지표로써 글루타치온 산화정도, GSSG/(GSH+2xGSSG)를 측정하였을 때 주로 해마에서 산화지표가 상승됨을 관찰하였다. 한편 산화성 스트레스가 세포손상으로 연결되는지를 알아보고자 지질과산화물을 측정하였다. 두 부위 모두에서 지질과산화물 형성의 증가가 있었으며 대뇌피질에서보다 해마에서 더 증가됨을 알 수 있었다. 지질과산화물 형성의 정도나 시간적 변화양상이 글루타치온 산화의 그것들과 유사하였다. 이러한 결과들은 허혈/재관류에 의해 산화성 스트레스가 형성되며 동시에 이러한 산화성 스트레스가 세포 손상을 초래함을 보여준다. 또한 산화성 스트레스 및 산화성 세포손상 정도가 대뇌피질보다는 해마에서 더 큰 것을 알 수 있었다. 그러나, 피질과 해마에서 HSP70의 기초발현(basal level) 정도는 차이가 없었다. 이는 해마의 취약성이 HSP70 발현 결핍에 기인하지 않았음을 나타낸다. 반면 허혈/재관류에 의한 HSP70의 발현유도는 해마조직에서 제대로 이주어지지 않았고 northern blot결과 이는 전사단계에서의 부친에 의한 것으로 나타났다. 이러한 결과들로 볼 때 허혈/재관류에 의한 뇌손상에서 HSP70 유도정도를 측정하는 것이 세포의 취약성을 예측할 수 있는 지표로 유용하게 사용될 수 있을 것으로 사료된다.

• 대한간호학회지
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• 제37권6호
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• pp.986-993
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• 2007

Purpose: The purpose of this study was to compare stress levels of elementary students according to three regional levels: a large city, a medium-sized city, and a rural area. Methods: This was a descriptive comparative survey using a convenience sample of 1,161 5th-and 6th-grade students. The stress level was measured by a stress scale that consisted of 65 items regarding personal characteristics, family, school, and peer factors. The data were analyzed by ${\chi}^2-test$, t-test, ANOVA and multiple regression using the SPSS 10.0 statistical program. Results: Overall, the mean stress scores reported by the participants were near the middle of a 5-point scale and the level of family-related stress was highest, followed by peer, school, and individual-related stress. Sixth-graders and female students showed higher stress levels than 5th-graders and male students, respectively. The participants reporting unsatisfaction with their lives and those living in large cities tended to have significantly higher stress levels. Conclusion: Grade, gender, life satisfaction, and regional levels were all significant factors associated with high stress levels among elementary students. Development of stress management programs for this specific population, especially targeting students who are female and living in large cities, is needed.

• 한국안전학회지
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• 제29권2호
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• pp.53-61
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• 2014

This study evaluated wind loads considering a local basic wind velocity and construction periods to define the level of applied wind loads for system supports. Structural responses of system supports were examined and compared to those of system supports with the level of wind loads following various standards and specifications for permanent and temporary structures. And, the maximum combined stress ratios were estimated to evaluate the structural safety of a considered system support. From results, it was found that the wind load level should be applied in accordance with construction periods when estimating the safety of system supports. Looking into the response by change of the basic wind velocity according to local regions, it is no need to consider wind loads in regions with the basic wind velocity of 30 m/s. However, it was analyzed that wind loads should be considered in the regions with the basic wind velocity of 40 m/s or above. In addition, wind loads should be considered in designing system supports located at the region with the basic wind velocity of 35 m/s starting from construction period of 1.5 years. The standard specification for temporary work was analyzed as an incorrect standard in evaluating wind loads, since it underestimated the response of system supports in accordance with the local basic wind velocity and construction periods.

• International Journal of Industrial Entomology and Biomaterials
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• 제19권2호
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• pp.229-235
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• 2009

We have cloned and characterized a lipocalin from the bumblebee Bombus ignitus (Bi-lipocalin). The Bi-lipocalin gene spans 2284 bp and consists of four exons coding for 270 amino acid residues. Sequence analysis revealed that Bi-lipocalin possesses three structurally conserved regions (SCTs) that characterize lipocalins. Recombinant Bi-lipocalin, expressed as a 37 kDa protein in baculovirus-infected insect cells, was N-glycosylated, indicating that the carbohydrate moieties are necessary for secretion. Tissue distribution analysis revealed ubiquitous expression of Bi-lipocalin in all tissues examined. Bi-lipocalin transcripts were upregulated by stress, such as wounding, $H_2O_2$ exposure, and external temperature shock. These results indicate that Bi-lipocalin is a stress-inducible protein that acts on wounding, $H_2O_2$ overexposure and temperature stimulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.529-534
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• 1998

To find out an adequate failure criterion in two-dimensional linear elastic crack problems, finite element programs, SED, which determine stress intensity factors $K_I, K_{II}$, crack angle and peak load by the minimum strain energy density failure criterion were developed. In this program, the conventional quadratic isoparametric elements were used in all regions except the crack tip zone where triangular singular elements with 6 nodes were used. The results of SED were compared with the results of those which followed by the maximum circumferential tensile stress criteria and those by the maximum energy release rate criteria and those by Jenq and Shah`s experiments of the same geometry and material properties. The maximum energy release rate criteria were better close to those of the Jenq and Shah`s experiments than the maximum circumferential tensile stress criteria and the minimum strain energy density criteria.

• 한국공작기계학회논문집
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• 제13권4호
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• pp.73-78
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• 2004

The conventional SLT(Shear Lag Theory) which has been proven that it can not provide sufficiently accurate strengthening predictions in elastic regime when the fiber aspect ratio is small. This paper is an extented work to improve it by modifying the load transfer mechanism called NSLT(New Shear Lag Theory), which takes into account the stress transfer across the fiber ends and the SCF(Stress Concentration Factor) that exists in the matrix regions near the fiber ends. The key point of the model development is to determine the major controlling factor among the material and geometrical coefficients. It is found that the most affecting factor is the fiber/matrix elastic modulus ratio. It is also found that the proposed model gives a good result that has the capability to correctly predict the elastic properties such as interfacial shear stresses and local stress variations in the small fiber aspect ratio regime.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권1호
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• pp.51-56
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• 2013

With the active development of hybrid electric vehicle (HEV), the application of interior permanent magnet synchronous motor (IPMSM) has been expanded. As wide driving region of IPMSM for electric vehicle (EV) traction motor is required, many studies are conducted to improve characteristics of a motor in both low and high-speed driving regions. A motor in high-speed driving region generates (produces) large stress to the rotor. Thus, the rotor needs to be designed considering the mechanical safety. Therefore, in this paper, we conducted stress analysis and electromagnetic analysis to determine the centerpost's distance which is considered important during the design of IPMSM for EV traction motor in order to secure mechanical safety and satisfy specifications of output requirement.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.955-962
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• 2006

This paper has the objects of deciding dynamic instability regions of thick plates on Pasternak foundation by finite element method and providing kinematic design data for mats and slabs of building structures. In this paper, dynamic stability analysis of tapered opening thick plate is done by use of Serendipity finite element with 8 nodes considering shearing strain of plate. To verify this finite element method, buckling stress and natural frequencies of thick pate with or without in-plane stress are compared with existing solutions. The results are as follow that this finite element solutions with 4x4 meshes are shown the error of maximum 0.56% about existing solutions, and obtained dynamic instability graph according with variation of opening positions.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.180-189
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• 1999

This paper describes the collapse characteristics of the rectangular tube under eccentric compressive load. Local buckling stress and maximum crippling load are investigated. A thin-walled tube under load is controlled by local buckling or yielding of material according to the ratio of thickness to width (t/b) of the cross section, and subsequent collapse of the section. The relationship can be divided into three regions : elastic , post-buckling and crippling . the load-displacement relationship is theoretically presented in each region by introducing the stress distribution of the cross section in the loading process. And the maximum load carrying capacity is derived in the closed form as a function of normal stress on the flange and web.