• 한국재료학회지
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• 제16권9호
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• pp.592-597
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• 2006

A deoxidized low-phosphorous (DLP) copper was processed by accumulative roll-bonding (ARB) for ultra grain refinement and high strengthening. Two copper sheets 1 mm thick, 30 mm wide and 300 mm long are first degreased and wire-brushed for sound bonding. The sheets are then stacked to each other, and roll-bonded by about 50% reduction rolling without lubrication at ambient temperature. The bonded sheet is then cut to the two pieces of same dimensions and the same procedure was repeated to the sheets up to eight cycles (${\varepsilon}{\sim}6.3$). TEM observation revealed that ultrafine grains were developed after the 4th cycle, and their size decreased at higher cycles. Tensile strength of the copper increased with the equivalent strain, and it reached 547 MPa which was 3 times higher than that of the initial material. It is concluded that the ARB process is an effective method for high strengthening of the DLP copper.

• Advances in materials Research
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• 제1권4호
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• pp.245-268
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• 2012

Results of isothermal torsional oscillation tests are reported on melts of linear low density polyethylene and isotactic polypropylene. Prior to rheological tests, specimens were annealed at various temperatures ranging from $T_a$ = 180 to $310^{\circ}C$ for various amounts of time (from 30 to 120 min). Thermal treatment induced degradation of the melts and caused pronounced decreases in their molecular weights. With reference to the concept of transient networks, constitutive equations are developed for the viscoelastic response of polymer melts. A melt is treated as an equivalent network of strands bridged by junctions (entanglements and physical cross-links). The time-dependent response of the network is modelled as separation of active strands from and merging of dangling strands with temporary nodes. The stress-strain relations involve three adjustable parameters (the instantaneous shear modulus, the average activation energy for detachment of active strands, and the standard deviation of activation energies) that are determined by matching the dependencies of storage and loss moduli on frequency of oscillations. Good agreement is demonstrated between the experimental data and the results of numerical simulation. The study focuses on the effect of molecular weight of polymer melts on the material constants in the constitutive equations.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.953-960
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• 2012

This paper reports the irradiation effect on the deformation behavior and tensile fracture properties of A533B RPV steel. An inverse identification technique using iterative finite element (FE) simulation was used to determine those properties from tensile data for the A533B RPV steel irradiated at 65 to $100^{\circ}C$ and deformed at room temperature. FE simulation revealed that the plastic instability at yield followed by softening for higher doses was related to the occurrence of localized necking immediately after yielding. The strain-hardening rate in the equivalent true stress-true strain relationship was still positive during the necking deformation. The tensile fracture stress was less dependent on the irradiation dose, whereas the tensile fracture strain and fracture energy decreased with increasing dose level up to 0.1 dpa and then became saturated. However, the tensile fracture strain and fracture energy still remained high after high-dose irradiation, which is associated with a large amount of ductility during the necking deformation for irradiated A533B RPV steel.

• International Journal of Computer Science & Network Security
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• 제22권12호
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• pp.85-90
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• 2022

The article is devoted to the consideration of the features of the application of criminal and legal countermeasures against cybercrime in the conditions of martial law. While conducting this research, we found an opportunity to formulate the author's recommendations for solving the most complex law enforcement problems, as well as to propose changes to the Criminal Code of Ukraine aimed at eliminating the flaws of the analyzed Law, the adoption of which will contribute to the achievement of higher efficiency of the relevant criminal law prescriptions. It is argued that the removal of the previously existing in the footnote of Art. 361 of the Criminal Code of a fundamentally important caveat regarding the fact that when assessing "significant damage", the mentioned property equivalent was to be taken into account only when such damage consisted in causing material damage, which led to a significant and unjustified narrowing of the scope of potential application of Part 4 of Article 361 of the Criminal Code.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.649-656
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• 2023

Recently, global warming has become severe, and regulation is established for carbon savings each field. its regulation is applied to various fields using IC engine such as automobile, ship, agricultural machine. Therefore engine block applied Common Rail Direct Injection(CRDI) technology, that carry out thermal-structure analysis to examine design. The thermal load about 900℃ by explosion was applied in cylinder. And pressure about 9 MPa(90 Bar) was applied to structure analysis. As a result, it was the highest at 185.99℃ at the top of cylinder. Static-structure analysis applied thermal load, that was shown maximum equivalent stress at 142.59 Mpa and Maximum principal stress 145.03 MPa, Minimum principal stress -149 MPa. When compare analysis results to material property, it design is safety structurally.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1229-1237
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• 2013

본 연구에서는 증분소성이론에 기초한 구형압입이론을 크리프 물성을 평가하기 위한 압입이론으로 확장했다. 먼저 크리프변형률 기울기가 일정한 지점을 유효 응력-변형률속도 최적 관측지점으로 선정했다. 구형압입시험 전산모사를 이용해 크리프 지수와 계수를 변화시켜 가면서 이에 따른 재료의 거동을 무차원 변수들 (${\xi}$, ${\psi}$)의 회귀식으로 표현해 크리프 물성평가를 위한 새로운 수치 접근법을 구축했다. 이를 토대로 구형압입시험으로부터 재료의 크리프지수 및 계수를 예측하는 물성평가 프로그램을 개발했다. 압입 하중-변위 곡선으로부터 크리프지수는 평균 1.5%, 크리프계수는 평균 1.0% 이내의 오차범위에서 물성치들을 얻을 수 있다.

• Journal of Astronomy and Space Sciences
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• 제22권4호
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• pp.441-450
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• 2005

유기재료(organic material)는 위성이나 우주비행체의 열을 조절하고 우주환경에 직접 노출되는 것을 차단하기 위하여 가장 흔하게 사용되는 재료 중 하나이다. 본 논문에서는 지상설비를 이용하여 모사한 우주환경에서 유기재료의 물성변화를 관찰하였다. 대표적인 위성용 유기 열조절 재료 중 하나인 2mil ITO(Indium Tin Oxide) coated aluminized KAPTON을 실험 대상으로 선택하였다. 양성자에 의한 단일 우주환경효과를 실험하기 위하여, 한국 원자력의학원의 MC-50 싸이클로트론(cyclotron)을 이용하여 양성자를 조사(irradiation)하였으며, 조사조건은 지구궤도 주변 최고의 양성자 발생기록인 1972년 8월의 최고치 상황을 적용하였다. 조사에너지는 평균 관측에너지인 30MeV으로 고정하였으며, 등가 조사량은 우주노출 시간 1년, 3년, 5년 및 10년을 기준으로 설정하였다. 분석과정은 인장강도를 측정하여 정량적 물성저하를 확인하였고, 전계방출 전자주사현미경 등으로 결정성변화와 노출표면의 손상을 분석하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.104-104
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• 2009

Critical dimensions has rapidly shrunk to increase the degree of integration and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate insulator layer and the low conductivity characteristic of poly-silicon. To cover these faults, the study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$ and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-silicon gate is not compatible with high-k materials for gate-insulator. To integrate high-k gate dielectric materials in nano-scale devices, metal gate electrodes are expected to be used in the future. Currently, metal gate electrode materials like TiN, TaN, and WN are being widely studied for next-generation nano-scale devices. The TaN gate electrode for metal/high-k gate stack is compatible with high-k materials. According to this trend, the study about dry etching technology of the TaN film is needed. In this study, we investigated the etch mechanism of the TaN thin film in an inductively coupled plasma (ICP) system with $O_2/BCl_3/Ar$ gas chemistry. The etch rates and selectivities of TaN thin films were investigated in terms of the gas mixing ratio, the RF power, the DC-bias voltage, and the process pressure. The characteristics of the plasma were estimated using optical emission spectroscopy (OES). The surface reactions after etching were investigated using X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES).

• 대한기계학회논문집A
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• 제35권5호
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• pp.549-554
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• 2011

최근 고온부품의 기술발전으로 고효율 가스터빈 발전설비들이 운전되고 있으나 국내의 가스터빈설비는 일일 기동정지를 반복 운전하므로써 열싸이클에 의한 블레이드와 베인의 재료물성은 급격히 나빠지고 있다. 현재 가스터빈 부품 교체와 정비는 제작사에 의존하고 있는 실정으로 이에 본 연구에서 독자적인 교체 및 정비 관리 기준을 위해 수명평가와 손상분석의 기초자료로 활용하고자 실제 운전된 가스터빈 고압 1단 블레이드와 베인의 사용시간별 손상거동을 분석하였다. 사용재의 블레이드는 등가운전시간(EOH)이 23,686, 27,909 및 52,859 이고 베인은 28,714 및 52,859 으로 운전시간이 증가함에 따라 ${\gamma}$'의 크기는 증가하고 형상은 구형 또는 판상으로 변형되었다. 블레이드는 leading edge영역, 베인은 center영역에서 가장 큰 미세조직의 열화가 관찰되었으며 이는 경도의 감소경향과 일치하였다. 열차폐 코팅층내 bond코팅층에서는 운전시간이 증가함에 따라 표면산화층의 두께가 증가하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.104-107
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• 2001

The fabricated La-modified lead titanate (PLT) thin flim without paling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method. $Pb_{1-x}La_{x}Ti_{1-x/4}O_{3}$ PLT (x=0.1) thin film having 10 mol% La content was deposited on a $Pt/TiO_{x}/SiO_{2}/Si$ substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is $6.6{\times}10^{-9}C/cm_{2}\cdot K$ without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are $1.03{\times}10^{-11}C\cdot cm/J$ and $1.46\times 10^{-9}C\cdot cm/J$, respectively. The PLT(10) thin film has voltage responsivity (Rv) of 5.15 V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity (D*) of the PLT(10) thin film are$9.93{\times}10^{-8}W/Hz^{1/2}$ and $1.81\times 10^{6}cmHz^{1/2}/W$ at the same frequency of 100 Hz, respectively. The results means that PLT thin film having 10 mol % La content is suitable for the sensing materials of pyroelectric IR sensors.