• Korean Journal of Materials Research
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• v.14 no.10
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• pp.688-695
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• 2004

The capacitor contact barrier(CCB) layers have been introduced in the FeRAM integration to prevent the Pt/Al reaction during the back-end processes. Therefore, the interdiffusion and intermetallic formation in $Pt(1500{\AA})/Al(3000{\AA})$ film stacks were investigated over the annealing temperature range of $100\sim500^{\circ}C$. The interdiffusion in Pt/Al interface started at $300^{\circ}C$ and the stack was completlely intermixed after annealing over $400^{\circ}C$ in nitrogen ambient for 1 hour. Both XRD and SBM analyses revealed that the Pt/Al interdiffusion formed a single phase of $RtAl_2$ intermetallic compound. On the other hand, in the presence of TiN($1000{\AA}$) barrier layer at the Pt/Al interface, the intermetallic formation was completely suppressed even after the annealing at $500^{\circ}C$. These were in good agreement with the predicted effect of the TiN diffusion barrier layer. But the conventional TiN CCB layer could not perfectly block the Pt/Al reaction during the back-end processes of the FeRAM integration with the maximum annealing temperature of $420^{\circ}C$. The difference in the TiN barrier properties could be explained by the voids generated on the Pt electrode surface during the integration. The voids were acted as the starting point of the Pt/Al reaction in real FeRAM structure.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.77-80
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• 2013

An analytical study on performance of superdetonative mode ram accelerator was conducted for understanding the S225 experimental result of ISL. It would be noticeable that ISL S225 experimental result could be analytically simulated with the assumptions of inlet shockwave, equilibrium combustion chemistry, temperature dependent specific heat, and C-J oblique detonation in superdetonative operation mode. As result, the S225 experiment could be affected by heat of aluminum. Also, this study showed that the improper assumption, like isentropic assumption on shockwave, or constant specific heat on combustion, might cause misunderstanding about experimental result.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.498-498
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• 2020

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1445-1449
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• 2005

The ram assembly is important equipment in fueling machine of PHWR(Pressurized Heavy Water Reactor) plant where fuel replacement is possible while the plant is in service. Troubles in the ram assembly can cause lots of difficulties in power plant operation. The ram assembly is typically composed of the B-ram, the L-Ram and the C-Ram. The B-ram is focused in this paper because it plays the most important role in the ram assembly. Among the ram fault phenomena, ram stuck phenomena are the most frequent cases in the B-ram, which has a ball screw mechanism driven by a hydraulic motor. Ram stuck phenomena are due to ball wear and damage in ball nut that increase in proportion to the number of fuel replacement. It is required to predict ram stuck phenomena before they occur. In this paper, a method is proposed for predicting ram stuck phenomena using a discrete wavelet transform. The discrete wavelet transform provides information on both the time and frequency characteristics of the input signals. The proposed method uses the frequency bandwidths of coefficients of discrete wavelet decompositions and detail coefficients of discrete wavelet transform to predict ram stuck phenomena. The signal used in this paper is a torque-related signal such as a hydraulic service outlet pressure signal in a hydraulic driving system or a current signal in a DC motor driving system. Finally, the validity of the proposed method is shown via experiment using ball nut characteristic test equipment that simulates ram stuck phenomena due to increased ball friction in ball nut.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.98-103
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• 2008

1T1C DRAM has been facing technological and physical constraints that make more difficult their further scaling. Thus there are much industrial interests for alternative technologies that exploit new devices and concepts to go beyond the 1T1C DRAM technology, to allow better scaling, and to enlarge the memory performance. The technologies of DRAM cell are changing from 1T1C cell type to capacitor-less 1T-gain cell type for more scalable cell size. But floating body cell (FBC) of 1T-gain DRAM has weak retention properties than 1T1C DRAM. FET-type 1T-FeRAM is not adequate for long term nonvolatile applications, but could be a good alternative for the short term retention applications of DRAM. The proposed nonvolatile refresh scheme is based on utilizing the short nonvolatile retention properties of 1T-FeRAM in both after power-off and power-on operation condition.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.4
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• pp.463-469
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• 2005

An attempt was made to analyze the factors affecting mating performance of rams in pen mating systems. Due to many types of social interactions, mating performance of rams may decrease or increase. Six intact Muzaffarnagari rams were used and divided into three dominant subordinate pairs by food and ewe competition test. For dominant rams subordinate ram became competitor and vice versa. In the first experiment, ram was exposed to ewe but the competitor ram was kept outside the pen with the facility of visibility only. In the second experiment each ram was exposed to ewe along with the competitor ram and in third experiment ram was exposed to ewes (two) along with competitor ram in observation pen. Recordings of different mating and agonistic behaviour were done in all the experiments. It was found that subordinate ram's mating behaviour was inhibited by mere presence of a dominant ram out side without physical contact. However, when ram exposed to oestrus ewe(s) along with competitor ram, both dominant and subordinate rams spent much of their time in guarding activities instead of mating. In addition dominant ram tried to curtail the subordinate ram mating by agonistic interaction like fight and butting. Different guarding activities were observed either as active or passive type depending on level of dominanace. It was concluded that in a limited space the interaction of two or more rams might affect the number of services adversely.

• The KIPS Transactions:PartC
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• v.10C no.2
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• pp.233-240
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• 2003

In this paper, an improved architecture of turbo codec for IMT-2000 is proposed. The encoder consists of an interleaver using an on-the-fly type address generator and a modified shift register instead of an external RAM, and the decoder uses a decreased number of RAM. The proposed architecture is simulated with C/VHDL languages, where BER (bit-error-rate) performances are generally in agreement with previous data by varying interaction numbers, interleaver block sizes and code rates.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.257-263
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• 2014

Background: Vascular endothelial growth factor (VEGF), an endothelial cell specific mitogen, has been implicated as a critical factor influencing tumor related angiogenesis. The aim of present study was to evaluate the relationship between VEGF +936C>T and +405C>G polymorphisms of VEGF with risk of breast cancer in Punjab, India. Materials and Methods: We screened DNA samples of 192 sporadic breast cancer patients and 192 unrelated healthy, gender and age matched control individuals for VEGF +936C>T and +405C>G polymorphisms using the PCR-RFLP method. Results: For the VEGF +405C>G polymorphism, we observed significantly increased frequency of GG genotype in cases as compared to controls and strong association of +405GG genotype was observed with three fold risk for breast cancer (OR=3.07; 95%CI 1.41-6.65; p=0.003). For the +936C>T polymorphism, significant associations of CT and combined CT+TT genotypes were observed with elevated risk of breast cancer (p=0.021; 0.023). The combined genotype combinations of GG-CC and GG-CT of +405C>G and +936C>T polymorphisms were found to be significantly associated with increased risk of breast cancer (p=0.04; 0.0064). Conclusions: The findings of the present study indicated significant associations of VEGF +936C>T and +405C>G polymorphisms with increased breast cancer risk in patients from Punjab, North India.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.3068-3086
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• 2022

Digital Forensics is gaining popularity in adjudication of criminal cases as use of electronic gadgets in committing crime has risen. Traditional approach to collecting digital evidence falls short when the disk is encrypted. Encryption keys are often stored in RAM when computer is running. An approach to acquire forensic data from RAM when the computer is shut down is proposed. The approach requires that the investigator immediately cools the RAM and transplant it into a host computer provisioned with a tool developed based on cold boot concept to acquire the RAM image. Observation of data obtained from the acquired image compared to the data loaded into memory shows the RAM chips exhibit some level of remanence which allows their content to persist after shutdown which is contrary to accepted knowledge that RAM loses its content immediately there is power cut. Results from experimental setups conducted with three different RAM chips labeled System A, B and C showed at a reduced temperature of -25C, the content suffered decay of 2.125% in 240 seconds, 0.975% in 120 seconds and 1.225% in 300 seconds respectively. Whereas at operating temperature of 25℃, there was decay of 82.33% in 60 seconds, 80.31% in 60 seconds and 95.27% in 120 seconds respectively. The content of RAM suffered significant decay within two minutes without power supply at operating temperature while at a reduced temperature less than 5% decay was observed. The findings show data can be recovered for forensic evidence even if the culprit shuts down the computer.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.257-257
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• 2016

최근에 메모리의 초고속화, 고집적화 및 초절전화가 요구되면서 resistive random access memory (ReRAM), ferroelectric RAM (FeRAM), phase change RAM (PRAM)등과 같은 차세대 메모리 기술이 활발히 연구되고 있다. 다양한 메모리 중에서 특히 resistive random access memory (ReRAM)는 빠른 동작 속도, 낮은 동작 전압, 대용량화와 비휘발성 등의 장점을 가진다. ReRAM 소자는 절연막의 저항 스위칭(resistance switching) 현상을 이용하여 동작하기 때문에 SiOx, AlOx, TaOx, ZrOx, NiOx, TiOx, 그리고 HfOx 등과 같은 금속 산화물에 대한 연구들이 활발하게 이루어지고 있다. 이와 같이 다양한 산화물 중에서 AlOx는 ReRAM의 절연막으로 적용되었을 때, 우수한 저항변화특성과 안정성을 가진다. 하지만, AlOx 박막을 형성하기 위하여 기존에 많이 사용되어지던 PVD (physical vapour deposition) 또는 CVD (chemical vapour deposition) 방법에서는 두께가 균일하고 막질이 우수한 박막을 얻을 수 있지만 고가의 진공장비 사용 및 대면적 공정이 곤란하다는 문제점이 있다. 한편, 용액 공정 방법은 공정과정이 간단하여 경제적이고 대면적화가 가능하며 저온에서 공정이 이루어지는 장점으로 많은 관심을 받고 있다. 본 연구에서는 sputtering 방법과 용액 공정 방법으로 형성한 AlOx 기반의 ReRAM에서 메모리 특성을 비교 및 평가하였다. 먼저, p-type Si 기판 위에 습식산화를 통하여 SiO2 300 nm를 성장시킨 후, electron beam evaporation으로 하부 전극을 형성하기 위하여 Ti와 Pt를 각각 10 nm와 100 nm의 두께로 증착하였다. 이후, 제작된 AlOx 용액을 spin coating 방법으로 1000 rpm 10 초, 6000 rpm 30 초의 조건으로 증착하였다. Solvent 및 불순물 제거를 위하여 $180^{\circ}C$의 온도에서 10 분 동안 열처리를 진행하였고, 상부 전극을 형성하기 위해 shadow mask를 이용하여 각각 50 nm, 100 nm 두께의 Ti와 Al을 electron beam evaporation 방법으로 증착하였다. 측정 결과, 용액 공정 방법으로 형성한 AlOx 기반의 ReRAM에서는 기존의 sputtering 방법으로 제작된 ReRAM에 비해서 저항 분포가 균일하지는 않았지만, 103 cycle 이상의 우수한 endurance 특성을 나타냈다. 또한, 1 V 내외로 동작 전압이 낮았으며 104 초 동안의 retention 측정에서도 메모리 특성이 일정하게 유지되었다. 결론적으로, 간단한 용액 공정 방법은 ReRAM 소자 제작에 많이 이용될 것으로 기대된다.