• 대한기계학회논문집B
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• 제32권11호
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• pp.832-840
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• 2008

Ablation occurs at irradiance beyond $10^9\;W/cm^2$ with nanosecond and short laser pulses focused onto any materials. Phenomenologically, the surface temperature is instantaneously heated past its vaporization temperature. Before the surface layer is able to vaporize, underlying material will reach its vaporization temperature. Temperature and pressure of the underlying material are raised beyond their critical values, causing the surface to explode. The pressure over the irradiated surface from the recoil of vaporized material can be as high as $10^5\;MPa$. The interaction of high power nanosecond laser with a thin metal in air has been investigated. The nanosecond pulse laser beam in atmosphere generates intensive explosions of the materials. The explosive ejection of materials make the surrounding gas compressed, which form a shock wave that travels at several thousand meters per second. To understand the laser ablation mechanism including the heating and ionization of the metal after lasing, the temporal evolution of shock waves is captured on an ICCD camera through laser flash shadowgraphy. The expansion of shock wave in atmosphere was found to agree with the Sedov's self-similar spherical blast wave solution.

• 한국표면공학회지
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• 제44권4호
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• pp.125-130
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• 2011

$Cr_2AlC$ compounds were synthesized by hot pressing, and oxidized between 900 and $1200^{\circ}C$ in air for up to 50 hours. They oxidized to a thin $Al_2O_3$ layer containing a small amount of $Cr_2O_3$with the liberation of carbon as CO or $CO_2$ gases. The consumption of Al to form the $Al_2O_3$ layer led to the depletion of Al and enrichment of Cr just below the $Al_2O_3$ layer, resulting in the formation of an underlying $Cr_7C_3$ layer. As the oxidation temperature and time increased, the $Cr_7C_3$ oxide layer and the underlying $Cr_7C_3$ layer thickened. The oxidation resistance of $Cr_2AlC$ was generally good due to the formation of the $Al_2O_3$ barrier layer.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.477-480
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• 2009

영상을 전송하는 과정에서 여러 가지 원인으로 열화가 발생하고 있으며 열화의 주된 원인은 노이즈에 의한 것으로 알려져 있다. 임펄스 잡음에 의해 훼손된 영상의 잡음을 제거하는 대표적인 방법은 SM필터가 많이 사용되고 있으며 이 필터는 영상의 에지영역에 특성이 저하되는 경향이 있다. 따라서 본 논문에서는 임펄스 잡음 환경에서 에지특성을 고려한 영상을 복원하기 위해 마스크의 형태 및 임펄스 잡음 확률을 이용한 비선형 필터를 제안하였다. 그리고 시뮬레이션을 통해 기존의 방법들과 그 성능을 비교하였다.

• 한국표면공학회지
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• 제55권6호
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• pp.408-416
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• 2022

In this study, the effect of Au-Sn alloy coating on reliability of electrical contacts was investigated via comparison with Au-Co alloy coating. The results show that Au-Sn alloy exhibited lower contact resistance and higher solder spreadability than those of Au-Co alloy after thermal aging. In the case of Au-Co alloy plating, the underlying Ni element diffused into Au-Co layer to form Ni oxides on surface during thermal aging, leading to increased contact resistance and decreased solder spreadability. Meanwhile, for Au-Sn alloy plating, Au-Ni-Sn metallic compound was formed at the interface between Au-Sn layer and underlying Ni layer. This compound acted as a diffusion barrier, thereby inhibiting the diffusion of Ni to Au-Sn layer during thermal aging. Consequently, Au-Sn alloy layer showed better contact reliability than that of Au-Co alloy layer.

• Biomolecules & Therapeutics
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• 제31권4호
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• pp.456-465
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• 2023

Cervical tumors represent a prevalent form of cancer affecting women worldwide; current treatment options involve surgery, radiotherapy, and chemotherapy. Angiogenesis, the process of new blood vessel formation, is a crucial factor in cervical tumor growth. The molecular mechanisms underlying the effects of the liver kinase B1 (LKB1/STK11) tumor suppressor protein on tumor angiogenesis have not been elucidated. Therefore, we investigated the role of LKB1 in cervical tumor angiogenesis both in vitro and in vivo in this study. Our results demonstrated that LKB1 inhibited cervical tumor angiogenesis by suppressing the expression of angiogenesis-related factors such as vascular endothelial growth factor (VEGF) and hypoxia inducible factor-1α. LKB1 directly affected both carcinoma and vascular endothelial cells, resulting in a significant reduction in tumor growth and angiogenesis. Furthermore, LKB1 was found to bind to VEGF receptor 2 (VEGFR-2) and target the VEGFR-2-mediated protein kinase B/mechanistic target of rapamycin signaling pathway in endothelial cells, thereby reducing cervical tumor growth and angiogenesis. Our study provides new insights into the molecular mechanisms underlying the anti-tumor and anti-angiogenic effects of LKB1 in cervical cancer. These findings will help develop new therapeutic strategies for cervical cancer.

• 비교문화연구
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• 제50권
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• pp.425-451
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• 2018

본고에서는 기존의 쌍형어 논의들의 쟁점들을 살펴보았다. 일반적으로 쌍형어는 공통의 어원에서 갈라져 나온 단어들의 쌍을 가리키지만 공시적으로 의미가 같고 형식의 유사성을 보이는 단어들의 쌍이나 문법 형태소들의 쌍을 가리키기도 한다. 본고는 전형적인 쌍형어는 공통의 어원을 가지는 단어들의 쌍이라고 보았다. 쌍형어는 의미와 형식의 유사성이나 차이에 따라 하위 유형화가 가능하다. 전형적인 쌍형어에서 가장 멀어진 것은 공통의 어원을 가지지는 않지만 의미가 같고 형식이 유사한 단어들의 쌍이라고 할 수 있다. 두 번째 쟁점은 쌍형어가 단어들의 쌍을 가리키는가 하는 점이다. 공통의 어원을 가지는 단어들의 쌍이 전형적인 쌍형어이나 조사나 어미의 경우에도 쌍형어를 인정한다면 조사 쌍형어나 어미 쌍형어의 존재가 가능할 것이다. 접미사의 경우에는 접미사 쌍형어의 인정이 가능할 수 있으나 접미사가 결합한 파생어가 쌍형어를 형성하므로 굳이 접미사 쌍형어를 인정할 필요는 없다고 보았다. 어미의 경우도 해당 어미가 결합한 활용형의 쌍형어를 인정할 수도 있으나 한국어의 어미가 통사단위로서의 성격이 강하다는 점을 고려하면 엄청나게 많은 활용형의 쌍형어를 인정하기보다는 해당 어미를 쌍형어라고 하는 쪽이 적절할 것이다. 마지막으로 어간 쌍형어나 어미 쌍형어 일부가 기저형 층위에서 일종의 이형태 관계를 이루는지에 관한 쟁점이 있을 수 있으나 본고에서는 하나의 어휘 항목 내에 속하는 경우에는 쌍형어에 속하지 않는 것으로 보았다. 이들은 일종의 복수 기저형에 해당한다고 할 수 있다.

• 무역상무연구
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• 제46권
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• pp.29-60
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• 2010

The incentive and reasons to publish FIDIC Conditions of Contract for Design, Build and Operate Projects(DBO Form) are manifold. It is partly a response to the increasing need for sophisticated project delivery methods in both the public and private sectors and the already widespread use of the FIDIC Yellow Book with operation and maintenance obligations and partly a response to the challenge to decrease maintenance cost to a minimum by means of a new procurement route. As a result, FIDIC has developed a new model form to meet this market place requirement. On the other hand, FIDIC did not simply adapt the Yellow Book but has developed a new form from it, whilst preserving the style of the already known FIDIC Forms and maintaining the wording where it was not necessary to change it for the purposes of a DBO Form. Moreover DBO Form fills up supposed gaps in other FIDIC Forms and ameliorates the claim management and dispute management framework. FIDIC DBO approach may be shortly summarized as follows. First, DBO Form provides for single project responsibility. Second, DBO Form has the clear objective of ensuring the use of a most reliable and efficient technology at the lowest life-cycle cost. Third, DBO Form is intended to operate as an effective quality increase in the design and construction of projects. Fourth, DBO Form is intended to provide significant benefits with regard to system integration and reduction of risks. Fifth, DBO Form accelerates and enhances completion schedule compliance. Sixth, DBO takes care of all three supporting pillars of sustainability(including economical, environmental and social elements). DBO Form is obviously a good starting point for negotiations and the preparation of calls for tenders, thus saving the parties time and money. However, existing cultural and legal differences, particular local conditions and the particular needs of some branches of the industry may require the form to be adapted according to the particular needs of a project. And Civil law practitioners are strongly recommended to verify carefully the underlying legal concepts and background of each clause of the General Conditions in order to avoid unnecessary and sometimes unnatural changes and amendments being made. Note that when preparing the Particular Conditions ensure that terminology is consistent and that existing inherent concepts should not be ignored.

• BMB Reports
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• 제46권12호
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• pp.617-622
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• 2013

Rac1 plays a key role in neurite outgrowth via reorganization of the actin cytoskeleton. The molecular mechanisms underlying Rac1-mediated actin dynamics in the cytosol and plasma membrane have been intensively studied, but the nuclear function of Rac1 in neurite outgrowth has not yet been addressed. Using subcellular fractionation and immunocytochemistry, we sought to explore the role of nuclear Rac1 in neurite outgrowth. bFGF, a strong agonist for neurite outgrowth in PC12 cells, stimulated the nuclear accumulation of an active form of Rac1. Rac1-PBR (Q) mutant, in which six basic residues in the polybasic region at the C-terminus were replaced by glutamine, didn't accumulate in the nucleus. In comparison with control cells, cells expressing this mutant form of Rac1 displayed a marked defect in extending neurites that was concomitant with reduced expression of MAP2 and MEK-1. These results suggest that Rac1 translocation to the nucleus functionally correlates with bFGF-induced neurite outgrowth.

• Geomechanics and Engineering
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• 제24권4호
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• pp.371-388
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• 2021

A novel flexibility-based beam-foundation model for inelastic analyses of beams resting on foundation is presented in this paper. To model the deformability of supporting foundation media, the Winkler-Pasternak foundation model is adopted. Following the derivation of basic equations of the problem (strong form), the flexibility-based finite beam-foundation element (weak form) is formulated within the framework of the matrix virtual force principle. Through equilibrated force shape functions, the internal force fields are related to the element force degrees of freedom. Tonti's diagrams are adopted to present both strong and weak forms of the problem. Three numerical simulations are employed to assess validity and to show effectiveness of the proposed flexibility-based beam-foundation model. The first two simulations focus on elastic beam-foundation systems while the last simulation emphasizes on an inelastic beam-foundation system. The influences of the adopted foundation model to represent the underlying foundation medium are also discussed.

• ETRI Journal
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• 제18권2호
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• pp.87-106
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• 1996

This paper proposes a new model as a framework for forecasting demand and technological substitution, which can accommodate different patterns of technological change. This model, which we named, "Adaptive Diffusion Model", is formalized from a conceptual framework that incorporates several underlying factors determining the market demand for technological products. The formulation of this model is given in terms of a period analysis to improve its explanatory power for dynamic processes in the real world, and is described as a continuous form which approximates a discrete derivation of the model. In order to illustrate the applicability and generality of this model, time-series data of the diffusion rates for some typical products in electronics and telecommunications market have been empirically tested. The results show that the model has higher explanatory power than any other existing model for all the products tested in our study. It has been found that this model can provide a framework which is sufficiently robust in forecasting demand and innovation diffusion for various technological products.