• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.88-91
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• 2003

Tungsten is widely used as a plug for the multi-level interconnection structures. However, due to the poor adhesive properties of tungsten (W) on $SiO_2$ layer, the Ti/TiN barrier layer is usually deposited onto $SiO_2$ for increasing adhesion ability with W film. Generally, for the W-CMP (chemical mechanical polishing) process, the passivation layer on the tungsten surface during CMP plays an important role. In this paper, the effect of oxidants controlling the polishing selectivity of W/Ti/TiN layer were investigated. The alumina ($Al_2O_3$) abrasive containing slurry with $H_2O_2$ as the oxidizer, was studied. As our preliminary experimental results, very low removal rates were observed for the case of no-oxidant slurry. This low removal rate is only due to the mechanical abrasive force. However, for Ti and TiN with $H_2O_2$ oxidizer, different removal rate was observed. The removal mechanism of Ti during CMP is mainly due to mechanical abrasive, whereas for TiN, it is due to the formation of metastable soluble peroxide complex.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.53-64
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• 2012

Deep and narrow welds can be produced by laser welding at high welding speeds with a narrow heat-affected zone (HAZ) and little distortion of the workpiece. This study aims to evaluate the usefulness of laser welding at automobile component manufacture. Microstructure observation, hardness test, tensile test and fatigue life test are performed by using the fiber laser welded SPFC590 steel sheets which is used widely in the manufacture of automotive seat frame. Three kinds of specimens are only a SPFC590 steel plate, quasi-butt joint plate and lap joint plate by laser welding. The following results that will be helpful to understand the static strength, fatigue crack initiation and growth mechanism were obtained. (1) The tensile strength of quasi butt joint specimens nearly equal to base metal specimens, but lap joint specimens fractured in shear area of weld metal. (2) The fatigue strength of quasi-butt joint specimen was approximately 8 percent lower than that of the base metal specimens. Furthermore, the lap joint specimens were less than 86 percent of the base metal specimens. (3) The lap joint fatigue specimens fractured at shear area in high level stress amplitude, while fractured at normal area in low level stress amplitude. From these results, the applicability of the laser welding to the automobile component is discussed.

• 동의생리병리학회지
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• 제25권3호
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• pp.438-444
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• 2011

Dojuk-San is known to be effective for treating a urinary diseases and stomatitis. However, its effects on the bone marrow-derived mast cell(BMMC) mediated allergy and inflammation mechanism remain unknown. In this study, the biological effects of Dojuk-San ethanol extract(DJS) were evaluated while focusing on its effects on the allergic mediator in phorbol 12-myristate 13-acetate(PMA) plus calcium ionophore A23187(A23187)-stimulated BMMCs. An investigation was also conducted to determine its effects on the production of several allergic mediators including interleukin-6(IL-6), prostaglandin D2($PGD_2$), leukotrieneC4(LTC4) and ${\beta}$-Hexosaminidase(${\beta}$-Hex). The results revealed that DJS inhibited the PMA plus A23187 induced production of IL-6, PGD2, LTC4 and ${\beta}$-Hex. Taken together, these findings indicate that DJS has the potential using in the treatment of allergy.

• 한국진공학회지
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• 제17권2호
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• pp.81-89
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• 2008

분자동역학을 이용하여 이온빔 스퍼터링 과정에서 원자의 거동을 연구하였다. Ar이온이 Au와 Pd(001) 표면에 다양한 에너지와 입사각도로 충돌할 때, 표면원자들 중 일부는 공간으로 떨어져 나갔으며, 반응 후 일부 원자들은 초기 표면보다 위쪽에 재증착 되는 현상이 관찰되었다. 재증착 원자의 수율은 스퍼터된 원자보다 Au의 경우 약 5배, Pd의 경우 약 3배 많이 입사 에너지와 입사 각도에 상관없이 발생됨을 확인하였다. 연속된 입사계산을 통해, 스퍼터링 과정에 발생되는 다양한 표면 패턴 형성 메커니즘을 식각만으로 설명하고 있는 종래의 개념과는 달리, 이온빔으로 인해 끊임없이 발생되는 재증착 원자들이 표면의 구조를 형성하는데 중요한 역할을 하는 것으로 확인되었다.

• 한국정밀공학회지
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• 제28권4호
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• pp.521-525
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• 2011

It is known that the low-intensity sound stimulation really affect to grow the cell. The cellular growth mechanism, however, does not been clearly identified even the effect on the low-intensity sound stimulation. The purpose of this study is to investigate the effect of low-intensity sound stimulation on the alveolar UC-MSC proliferation. Before the low-intensity sound stimulation is applied, the UC-MSC are cultured for 24 hours to facilitate their attachments. The cells are divided into two groups. And each was exposed to a medium with or without the low-intensity ultrasound stimulation at 71dB intensity level. The UC-MSC are again divided into three treatment groups of group 1, 2, and 3 and exposed to a frequency at 50Hz, 100Hz, and 1000Hz, respectively. In the results, it is investigated that the growth rates of UC-MSC for the stimulated groups were higher than those of control groups. In 1000Hz frequency, the number of UC-MSC cell is significantly higher than control groups (p>0.05). We would put the hypothesis that the cell growth could be enhanced by an appropriate low-intensity sound stimulation.

• 한국지반공학회논문집
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• 제27권12호
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• pp.39-52
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• 2011

본 연구에서는 유한요소해석 및 전단강도 감소기법을 적용하여 가압식 그라우팅 쏘일네일로 보강된 사면의 시공 단계를 고려한 사면안정 해석을 수행하였으며 무보강 자연사면 및 중력식 그라우팅 쏘일네일로 보강된 사면의 안전율과 비교함으로써 가압식 그라우팅 쏘일네일의 사면 보강효과를 분석하였다. 그 결과, 가압식 그라우팅 쏘일네일로 보강된 사면의 안전율이 중력식 그라우팅 쏘일네일로 보강된 사면에 비해 50% 이상 크게 나타났으며, 쏘일네일의 길이가 증가할수록 가압에 따른 보강효과가 우수한 것으로 나타났다. 또한 가압에 의해 사면 활동파괴영역이 확대됨에 따라 사면 전단저항 능력이 증가하는 것을 확인하였으며, 쏘일네일의 인발저항력이 사면보강에 가장 큰 영형을 미치는 것을 알 수 있었다.

• Geomechanics and Engineering
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• 제14권4호
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• pp.345-354
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• 2018

Currently, layered geogrid method (LGM) is the commonly practiced technique for reinforcement of slopes. In this paper the geogrid-box method (GBM) is introduced as a new approach for reinforcement of rock-soil slopes. To achieve the objectives of this study, a laboratory setup was designed and the slopes without reinforcements and reinforced with LGM and GBM were tested under the loading of a circular footing. The effect of vertical spacing between geogrid layers and box thickness on normalized bearing capacity and failure mechanism of slopes was investigated. A series of 3D finite element analysis were also performed using ABAQUS software to supplement the results of the model tests. The results indicated that the load-settlement behavior and the ultimate bearing capacity of footing can be significantly improved by the inclusion of reinforcing geogrid in the soil. It was found that for the slopes reinforced with GBM, the displacement contours are widely distributed in the rock-soil mass underneath the footing in greater width and depth than that in the reinforced slope with LGM, which in turn results in higher bearing capacity. It was also established that by reducing the thickness of geogrid-boxes, the distribution and depth of displacement contours increases and a longer failure surface is developed, which suggests the enhanced bearing capacity of the slope. Based on the studied designs, the ultimate bearing capacity of the GBM-reinforced slope was found to be 11.16% higher than that of the slope reinforced with LGM. The results also indicated that, reinforcement of rock-soil slopes using GBM causes an improvement in the ultimate bearing capacity as high as 24.8 times more than that of the unreinforced slope.

• Journal of Ginseng Research
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• 제44권4호
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• pp.593-602
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• 2020

Background: Heat stress orchestrates neurodegenerative disorders and results in the formation of reactive oxygen species that leads to cell death. Although the immunomodulatory effects of ginseng are well studied, the mechanism by which ginseng alleviates heat stress in the brain remains elusive. Methods: Rats were exposed to intermittent heat stress for 6 months, and brain samples were examined to elucidate survival and antiinflammatory effect after Korean Red Ginseng (KRG) treatment. Results: Intermittent long-term heat stress (ILTHS) upregulated the expression of cyclooxygenase 2 and inducible nitric oxide synthase, increasing infiltration of inflammatory cells (hematoxylin and eosin staining) and the level of proinflammatory cytokines [tumor necrosis factor α, interferon gamma (IFN-γ), interleukin (IL)-1β, IL-6], leading to cell death (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay) and elevated markers of oxidative stress damage (myeloperoxidase and malondialdehyde), resulting in the downregulation of antiapoptotic markers (Bcl-2 and Bcl-x_L) and expression of estrogen receptor beta and brain-derived neurotrophic factor, key factors in regulating neuronal cell survival. In contrast, KRG mitigated ILTHS-induced release of proinflammatory mediators, upregulated the mRNA level of the antiinflammatory cytokine IL-10, and increased myeloperoxidase and malondialdehyde levels. In addition, KRG significantly decreased the expression of the proapoptotic marker (Bax), did not affect caspase-3 expression, but increased the expression of antiapoptotic markers (Bcl-2 and Bcl-x_L). Furthermore, KRG significantly activated the expression of both estrogen receptor beta and brain-derived neurotrophic factor. Conclusion: ILTHS induced oxidative stress responses and inflammatory molecules, which can lead to impaired neurogenesis and ultimately neuronal death, whereas, KRG, being the antioxidant, inhibited neuronal damage and increased cell viability.

• Journal of Plant Biology
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• 제31권2호
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• pp.91-100
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• 1988

The effect of Ca2+ and polyamines on the activity $\beta$-glucan synthetase II(GSII) related to cell wall synthesis was studied in carrot suspension cultured cells. The activity of GS II is four times higher than that of $\beta$-glucan synthetase I in carrot suspension cultured cells and in vitro expreiment, the activity of GSII was increased in response to increase in concentration of Ca2+ and polyamines. When carrot suspension cultured cells were incubated together with Ca2+ and polyamines, the GSII activity was high at 0.1mM of Ca2+ and 1mM of putrescine. Also, polycationic poly-L-lysine and poly-L-ornithine increased about 50% the GSII activity than that of the control, respectively. These results may imply that Ca2+ and polyamines were related to the enzyme activity as a polycationic nature. In addition, verapamil as the calcium channel blocker and flunarizine as an antagonist of calcium mechanism in cytoplasm decreased GSII activity ramarkably, Ca2+ and calmodulin stimulated GSII activity as Ca2+ of free ion rather than Ca2+ calmodulin complex. The effect of 2,4-D on the GSII activity in culture medium is shown to be low at 0.1mg per liter and GSII activity increased about 30% more than that of the 0.1mg/l at the range of 0.3-1.0mg per litere. Cummulative results suggest that Ca2+ and polyfamines stimulate the cell wall synthesis by means of the enhancement of GSII activity responsible for synthesizing the cell wall components.

• 한국운동역학회지
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• 제23권1호
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• pp.85-90
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• 2013

Efficient gait is compensate for a lack of exercise, but the wrong walking can cause disease that joints, muscles, brain and body structure(Scott & Winter, 1990). Also many researchers has been studied gait of positive mechanism using analytical methods kinetic, kinematic. This study is to identify nature of knee adduction moment, depending on different foot progression angle and the movement of rotation of pelvis and body. Health study subject conducted intended walking with three different angles. The subjects of this study classified three types of walking; walk erect, pigeon-toed walk and an out-toed gait. Ten university students of K without previous operation and disease record selected for this study. For accuracy of this study, three types of walking carried out five times with 3D image analysis and using analysis of ground reaction force to analyze nature of knee adduction moment and the movement of rotation of pelvis and body. Firstly, the HC(heel contact) section value of intended walk erect, pigeon-toed walk and an out-toed gait was not shown statistically significant difference but TO(toe off) section value was shown that the pigeon-toed walk statistically significant. The value of pigeon-toed walk was smallest knee adduction moment(p< 0.005). Secondly, X axis was the change of rotation movement body and pelvis when walk erect, pigeon-toed walk and an out-toed gait. Shown statistically Y axis was not shown statistically significant but Z axis statistically significant(p<0.05). These result show the significant differences on TO section when walking moment reaches HC, it decides the walking types and rotates the foot.