• 소성∙가공
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• 제20권1호
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• pp.48-53
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• 2011

Fasteners are used to join the various electronic products and machines. So, the quality and reliability of the fastener are strongly requested. In this study, the analyses of the multi-stage cold forging of TORX screws for storage parts are carried out. In manufacturing of TORX screws, crack and folding defects are observed. Therefore, the analysis is focused on the prediction of the defects. Based on the analysis results, the upper die and process conditions are redesigned to reduce the defects. The upper die shape for preform forming is redesigned to prevent folding and sharp shape change. The Cockroft-Latham damage criterion is introduced to predict the crack initiation. Analysis results shows that the maximum Cockroft-Latham damage value is decreased by 40% in the forming using the modified upper die.

• 마이크로전자및패키징학회지
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• 제22권1호
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• pp.27-34
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• 2015

The correlation between crack propagation and localized recrystallization are compared in a series of cross section analyses on thermal cycled edgebond and underfilm material applied wafer level chip scale package (WLCSP) components with a baseline of no-material applied WLCSP components. The results show that the crack propagation distribution and recrystallization region correlation can explain potential degradation mechanisms and support the damage accumulation history in a more efficient way. Edgebond material applied components show a shift of damage accumulation to a more localized region, thus potentially accelerated the degradation during thermal cycling. Underfilm material applied components triggered more solder joints for a more wider distribution of damage accumulation resulting in a slightly improved thermal cycling performance compared to no-material applied components. Using an analysis on localized distribution of recrystallized areas inside the solder joint showed potential value as a new analytical approach.

• 소성∙가공
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• 제16권6호
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• pp.426-431
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• 2007

Hydroformability and fracture criteria of FE analysis based on ductile fracture were investigated in warm hydroforming of A16061 tube. To evaluate the hydroformability, uni-axial tensile test and bulge test were performed at room temperature and $200^{\circ}C$. The measured flow stresses were used as input parameters for FE analysis. The damage values were calculated by FE analysis based on ductile fracture criteria at maximum radius of free bulged tubes. Damage values were compared of hexagonal shaped hydroformed parts. As a result, the formability by critical damage value for extruded tube is lower than that of full annealed tube up to 0.5.

• Journal of Information Display
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• 제5권1호
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• pp.1-6
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• 2004

Ion shower doping with a main ion source of $P_2H_x$ using a source gas mixture of $PH_3/H_2$ was conducted on excimer-laser- annealed (ELA) poly-Si. The crystallinity of the as-implanted samples was measured using a UV-transmittance. The measured value of as-implanted damage was found to correlate well with the one calculated through/obtained from TRIM-code simulation. The sheet resistance was found to decrease as the acceleration voltage increased from 1 kV to 15 kV at a doping time of 1 min. However, it increases as the acceleration voltage increases under severe doping conditions. Uncured damage after furnace annealing is responsible for the rise in sheet resistance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.253-256
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• 2006

The HPFRCCs show the multiple crack and damage tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For practical application, it is needed to investigate the fractural behavior and of HPFRCCs and understand the micro-mechanism of cement matrix with reinforcing fiber. The objectives of this paper are to examine the compressive behavior, fracture and damage process of HPFRCC by acoustic emission technique. Total four series were tested, and the main variables were the hybrid type, polyethylene (PE) and steel cord (SC), and fiber volume fraction. The damage progress by compressive behavior of the HPFRCCs is characteristic for the hybrid fiber type and volume fraction. And from acoustic emission (AE) parameter value, it is found that the second and third compressive load cycles resulted in successive decrease of the ring-down count rate as compared with the first compressive load cycle.

• 대한토목학회논문집
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• 제30권1B호
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• pp.23-31
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• 2010

천변저류지의 조성에 관한 기존의 연구는 천변저류지의 홍수조절 효과분석이나 유량변화 등을 이용하여 그 효과를 판단하고 적용하여 왔다. 그러나, 이와 같은 분석방법은 천변저류지의 조성에 의한 경제적인 효과를 명확하게 제시할 수 없으므로 천변저류지의 타당성과 역할을 정확하게 평가하고 알리기에는 한계가 있다. 본 연구에서는 천변저류지 조성에 따른 홍수 조절 효과와 수질개선효과 및 생태적인 효과를 경제적인 가치로 산정하고 이를 정량화하였다. 이를 위하여 경상남도 창녕군에 위치한 우포늪 지역을 대상으로 분석을 수행하였으며, 우포늪의 천변저류지 조성에 따른 경제적인 가치는 평균 819억원으로 산정되었다. 본 연구에서 제시한 경제적 가치 평가는 천변저류지의 효과 및 중요성을 판단하는데 기여할 수 있을 것으로 판단된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.911-916
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• 2005

Noise map is a presentation of existing data or predicted noise situation in terms of noise indicator. However, it has shortcoming for assessing the number of people exposed, or the number of dwellings affected to any relevant limit values of noise level in certain areas. In this study, so called over-ride value noise mapping is proposed to make up for the shortcoming by using over-ride function of object-oriented programming and it is to show the guard of the area where it is satisfied the standard of option, or it is not satisfactory. Over-ride value noisemap data is combined with topography layer, population and house statistics, and GIS space statistical analysis. The over-ride value noise mapping can also he applied to make the road traffic noisemap, the railroad noisemap, the aircraft noisemap, and the industrial site noisemap This can express noise damage information more exactly.

• 한국소음진동공학회논문집
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• 제15권7호
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• pp.859-864
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• 2005

Noise map is a presentation of existing data or predicted noise situation in terms of noise indicator. However, it has shortcoming for assessing the number of people exposed, or the number of dwellings affected to any relevant limit values of noise level in certain areas. In this study, so called over-ride value noise mapping is Proposed to make up for the shortcoming by using over-ride function of object-oriented programming and it is to show the guard of the area where it is satisfied the standard of option, or it is not satisfactory. Over-ride value noise map data is combined with topography layer, population and house statistics, and GIS space statistical analysis. The over-ride value noise mapping can also be applied to make the road traffic noise map, the railroad noise map, the aircraft noise map, and the industrial site noise map. This can express noise damage information more exactly.

• Earthquakes and Structures
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• 제10권2호
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• pp.367-388
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• 2016

Eccentrically braced frames (EBFs) represent an attractive lateral load resisting steel system to be used in areas of high seismicity. In order to assess the likely damage for a given intensity of ground shaking, fragility functions can be used to identify the probability of exceeding a certain damage limit-state, given a certain response of a structure. This paper focuses on developing a set of fragility functions for EBF structures, considering that damage can be directly linked to the interstorey drift demand at each storey. This is done by performing a Monte Carlo Simulation of an analytical expression for the drift capacity of an EBF, where each term of the expression relies on either experimental testing results or mechanics-based reasoning. The analysis provides a set of fragility functions that can be used for three damage limit-states: concrete slab repair, damage requiring heat straightening of the link and damage requiring link replacement. Depending on the level of detail known about the EBF structure, in terms of its link section size, link length and storey number within a structure, the resulting fragility function can be refined and its associated dispersion reduced. This is done by using an analytical expression to estimate the median value of interstorey drift, which can be used in conjunction with an informed assumption of dispersion, or alternatively by using a MATLAB based tool that calculates the median and dispersion for each damage limit-state for a given set of user specified inputs about the EBF. However, a set of general fragility functions is also provided to enable quick assessment of the seismic performance of EBF structures at a regional scale.

• Journal of Nutrition and Health
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• 제36권3호
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• pp.255-261
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• 2003

Food irradiation has been steadily increasing in many countries in line with increasing international trade and concerns about naturally occurring harmful contaminants in food. Although irradiation provides an excellent safeguard for the consumer by destroying almost 100% of harmful bacteria, it is necessary to ensure the safety of irradiated foods. This study was performed to investigate the effect of an irradiated diet on lipid peroxidation in the plasma, liver, small intestinal mucosa, and lymphocyte DNA damage in mice. Eight-week old ICR mice were assigned to two groups to receive either non-irradiated or irradiated (10 kGy) diets containing 20.38% fish powder and 6.06% sesame seeds for 4 weeks. The resulting changes in the degrees of lipid peroxidation were evaluated based on the level of plasma and liver thiobarbituric acid reactive substance (TBARS), transmission electron micrograph of jejunal mucosa, and free radical-induced oxidative DNA damage in lymphocytes, as measured by alkaline comet assay (single cell gel electrophoresis). The peroxide values of the gamma irradiated diet were measured every week, and the sample for comet assay was taken at the end of the four week experimental period. There was no significant difference in food efficiency ratio between the two groups. The peroxide values of the diet were immediately increased to 35.5% after gamma irradiation and kept on increasing during storage. After 4 weeks, no differences in tissue or plasma TBARS value were observed between the two groups, but epithelial cells of jejumum showed osmiophillic laminated membranous structures, considered as myelin figures,. The oxidative DNA damage expressed as tail moment (TM) increased 30% in the blood lymphocytes of the mice fed the irradiated diet. In conclusion, the comet assay sensitively detected differences in lymphocyte DNA damage after feeding with the irradiated diet for 4 weeks. However, in order to ensure the safety of irradiated foods, it would be more useful to conduct a long-term feeding regimen using an irradiated diet and examine the level of lipid peroxidation and the state of oxidative stress in a greater range of organs.