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To investigate the reproducibility and I–V non-linearity characteristics in resistive-switching random-access memory (RRAM), we studied the switching characteristics through Pt/TiO2 interface control using a non-stoichiometric TiO2−x/TiN interface formation in a resistive switching Pt/TiO2/TiN stack. Using the TiO2−x/TiN interface instead of the TiO2/TiN interface induced nearly forming-free switching, decreased the reset current, suppressed the gradual reset process, and resulted in faster switching by electric pulse. These results indicate that the Pt/TiO2 interface experienced reduced oxygen-vacancy-mediated switching. The discrepancy between the reduced oxygen-vacancy-mediated switching and the initially large number of oxygen vacancies can be resolved via the oxygen vacancy distribution dependent field effect. To clarify this process, we performed reaction-diffusion-drift model simulations. The drift velocity, which was calculated using the vacancy distribution, described the dynamic movement, and the simulation results supported the experimentally observed faster switching response. The field effect, which provided successive feedback between the drift velocity and vacancy distribution, can potentially be exploited to generate vacancy-designed devices.

In this article the recent progress in the elements of EUV lithography is presented. Source power around 205W was demonstrated and further scaling up is going on, which is expected to be implemented in the field within 2017. Source availability keeps improving especially due to the introduction of new droplet generator but collector lifetime needs to be verified at each power level. Mask blank defect satisfied the HVM goal. Resist meets the requirements of development purposes and dose needs to be reduced further to satisfy the productivity demand. Pellicle, where both the high transmittance and long lifetime are demanded, needs improvements especially in pellicle membrane. Potential issues in high-NA EUV are discussed including resist, small DOF, stitching, mask infrastructure, whose solutions need to be prepared timely in addition to high-NA exposure tool to enable this technology.

As an emergency encountered in orthopedic practice requiring prompt diagnosis and aggressive treatment, necrotizing fasciitis around the hip must be discriminated from Fournier gangrene. The current case report describes a patient who suffered from bilateral type I necrotizing fasciitis around the hips, which was alleviated by prompt surgical debridement and intensive postoperative care.

산업의 고도화 및 새로운 기계의 도입, 화학물질 사용 등 산업재해의 다양한 양상과 더불어 생산설비들의 자동화, 대형화로 인해 산업재해 발생의 양상이 점차 다양해지고 있다. 국내 산업재해는 OECD(Organization for Economic Cooperation and Development) 경제협력개벌기구대비, 상대적 하위수준에 있어 기업 발생 산업재해는 근로자들의 심리적 및 치교와 보상 손실에도 타격이 되어 기업 총생산과 이윤 추구에도 중요문제가 야기되고 있다. 더불어, 장애자와 사망유족들의 증가로 생활 안정문제 등 사회적 문제도 제기된다. 이러한 동기에서 본 논문은 산업재해 통계와 산재예방 사업을 분석하고, 시스템다이내믹스 법론의 이용하여 산업재해율을 예측하고 평가하는 모델을 개발하였다. 모델은 근로자수 모델, 재해자수 모델, 재해율 모델 등 총 12개의 모델로 구성되었고, 규모별 분석에서는 근로자수를 기준으로 12개 그룹으로, 업종별 분석에서는 제조업, 건설업 등 총 10개의 업종으로 구분하여 개발하였다. 개발된 모델을 토대로 업종별 규모별 산업재해율을 예측하고 산재예방사업을 다각도로 평가하는 방법론을 제시하였다.

In this study, the enhancement of the silicon etch rate with the heavy doping of phosphorus and arsenic was studied during cyclic selective epitaxial growth process using batch-type equipment. The reaction between molecular chlorine and heavily doped silicon was stimulated during the initial stage of cyclic SEG process at low temperature lower than 700° to induce voids at the interface. Heavy doping of n-type dopants into active regions also brought about the decrease in the growth rate of SEG process. It was possible to attain a stable process window by the elaborate control of total amount ratio of SiH4/Cl2. The window provided the robust interface between SEG silicon and active regions as well as the selectivity to an oxide layer. Vertical diodes which were realized within the window revealed eligible on- and off-current characteristics for cell switches applicable to next generation cross-point memories.

Protective effect of ethanol extract from Hericium erinaceus cultivated with Artemisia capillaries (HEAC) on gastric mucosal damage induced by 0.15M HCl in ethanol in rats was evaluated. HEAC showed higher potent protective effect on gastritis with effective dose 50 (ED50) value of 22.6mg/kg compared those of selbex and stillen at 46.5 and 44.2 mg/kg, respectively, the presently used medicines for treating gastritis. ichloromethane fraction showed a dose-dependent protective effect on gastritis with ED50 value of 18.1 mg/kg. The biologically active component of dichloromethane fraction derived from HEAC ethanolic extract was characterized by spectroscopic analysis as scoparone with protective rate of 93% and ED50 value of 4.2 mg/kg on gastritis. Taken together, administration of HEAC and scoparone provided protective effect on the gastric lesion induced by ethanol-HCl and may therefore be a promising drug for treatment of gastritis and gastric ulcer.

cis -(3R,5R)-Atorvastatin Ca (1) used for hyperlipidemia have four stereomers. However, It is very difficult to prepare stereoselective stereomers. In this paper, the reduction of 3,5-diketo atorvastatin ester (3) was performed using Me 4 NHB(OAc) 3 in acetic acid as a reductant and showed excellent stereoselectivity in the double reduction of 3,5-diketo atorvastatin ester (3). As a result, reduction of compound 3 by Me 4 NHB(OAc) 3 was purely obtained with cis -(3R,5R)-atorvastatin ester (4) of 1.5% and trans -(3R,5S)-atorvastatin ester (5) of 98.5%. Also, cis-(3R,5R)-atorvastatin Ca (1) and trans-(3R,5S)-atorvastatin Ca (7) were used to determine efficacy in the treatment of liver damage and hyperlipidemia induced by a high-fat diet in rats and to study the performance of the January 2010 experient was conducted. As a result, total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), and triglyceride (TG) levels of compound 1 and 7 groups were 93.0±0.5, 43.5±0.8, 40.4±1.4, 45.6±0.9 mg/㎗ and 110.0±0.7, 33.3±0.6, 65.8±1.9, 54.8±1.2 mg/㎗, respectively. Atherogenic index (AI) and cardiac risk factor (CRF) in compound 1 and 7 were 1.14±0.05, 2.14±0.05 and 2.31±0.06, 3.31±0.06, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were 51.9±4.6, 16.0±2.1 IU/l and 75.8±4.4, 35.1±9.7 IU/l. Taken together, while compound 1 treat against high-fat diet-induced hyperlipidemia by attenuating hepatic lipid depots and reducing oxidative stress, compound 7 group had a low curative effect on hyperlipidemia induced by a high-fat diet in rats. These findings suggest that new method about synthesis of stereoselective stereomers and indicate that it may consider using in a clinical trial.

Abrupt changes in sidewall profile were induced in pulsed plasma etch process for high aspect ratio isolation trench structuring. Impacts of operational parameters when applying pulsed RF bias power were investigated. Silicon sidewall chipping problems were removed mainly by increasing bias power level and pulse frequency. The chemical sensitivity of O2 has shown decreased in extremely narrow trench spaces of high pattern density

Fungicidal activity against phytopathogenic fungi of diarylthiazole compound of N-[4-(4-fluoro) phenyl-2-(N-methyl)piperidin-4-yl-thiazol-5-yl]pyrimidin-2-yl-N-(3-hydroxy-methyl)phenylamine (I) have been determined to be a superior and compound I was used as the leading compounds in this study. Furthermore, the synthesis of this compound was conducted by reacting them with four functional groups, N-cyclopropyl, N-cyclopentyl, N-cyclohexyl, and N-isopropylamine instead of the phenylamine. Also, 2-aminothiazole, 2-(N-ethoxycarbonyl)piperidin-4-yl, and 2-piperidin-4-ylthiazole were introduced as the leads instead of the 2-aminothiazole group of compound I. From this scheme, VIII-1∼VIII-4 and XII-1∼XIV-4 compounds were newly synthesized and their structures were confirmed by 1H-NMR-spectrum. The fungicidal activities of all the synthesized compounds against Phytophthora capsici were examined using the whole plant method. While the EC50 value of the commercial fungicide dimethomorph and I was 4.26 mM and that of N-[4-(4-fluoro phenyl-2-(N-methyl)piperidin-4-yl-thiazol-5-yl]pyrimidin-2-yl-cyclopropylamine (XIV-2) on P. capsici was 0.84 mM. Among the XII-1∼XIV-4 chemicals, XIV-2 showed the most potential antifungal activity in vivo. Therefore, XIV-2 can be considered as a viable candidate for the control of phytopathogenic diseases characterized by P. capsici infection, and further studies will be conducted on the mode of action XIV-2.

APP based on the smart phone is being utilized to various scopes such as medical services in hospitals, financing services at banks and credit card companies, and ubiquitous technologies in companies and homes etc. In this service environment, exposures of smart phones cause loss of assets including leaks of official/private information by outsiders. Though secret keys, pattern recognition technologies, and single image authentication techniques are being applied as protective methods, but they have problems in that accesses are possible by utilizing static key values or images like pictures. Therefore, this study proposes a face authentication technology for protecting smart phones from these dangerous factors and problems. The proposed technology authenticates users by extracting key frames of user`s facial images by real time, and also controls accesses to the smart phone. Authentication information is composed of multiple key frames, and the user` access is controlled by distinction algorism of similarity utilizing DC values of image`s pixel and luminance.

To address the scalability of phase change memory (PCM), we study a 1-D thickness scaling effect on threshold switching voltage (Vth), Vth drift, high resistance state (RESET) resistance (RRESET) drift, and crystallization temperature (Tcrys). We use a pseudo three-terminal device to accurately correlate the amorphous region thickness to the observed characteristics. The pseudo 3-terminal device is a fully functional PCM cell and enables 1-D thickness scaling study down to 6 nm without the need for ultrafine lithography. Vth scales down to 0.65-0.5 V (at 25°C-75°C) for 6-nm-thick Ge2Sb2Te5 (GST), showing that stable read operation is possible in scaled PCM devices. The Vth drift measurement suggests that Vth drift can be attributed to threshold switching field (Eth) drift, whereas Vth0, i.e., Vth at zero thickness, stays almost constant. RRESET drift shows no dependence on the amorphous GST thickness. Tcrys is ~175°C for the device with 6-nm-thick GST, compared with ~145°C of thick GST. From the 1-D scaling study, no significant hurdles against scaling are found down to 6 nm. Further study of scaling effect on endurance and development of scalable selection device is needed to assess the ultimate scalability of PCM.

We studied the misalignment between active and gate layer in terms of silicon dislocation caused by high temperature anneal process in SOG based STI gap-fill process. The SOG process is one of good candidates to overcome gap-fill limitation due to its excellent gap-fill characteristics. However, the SOG process needs high temperature anneal process to convert from Si-H, N-H to Si-O bond, which leads to the misalignment due to large stress change. We suggest that silicon defect is generated from ion bombardment at trench etch process and accelerated from hysteresis at anneal process. The O2 cure process is known as one of feasible methods to cure silicon damage through recrystallization. Based on this model, the misalignment was significantly improved as removing the defect through O2 cure process following trench etch process.

Twenty five compounds isopropylmethylphenyl benzenesulfonate derivatives of thymol (1), 4-isopropyl-3-methylphenol (2), 5-isopropyl-3-methylphenol (3), 4-isopropylphenol (4), and 2-isopropylphenol (5) derivatives were synthesized. These compounds were analyzed for their structural confirmation with IR, GC/MS, and -NMR. Synthetic compounds were tested against phytopathogenic fungi activities such as Pyrcularia grisea, Rhizoctonia solani, Phytophthora infestans, Colletotrichum orbiculare, and Sphaerotheca fusca. 2-Isopropyl-5-methylphenyl o-toluenesulfonate (1a), 2-isopropylphenyl 2,4,5-trichloro-benzenesulfonate (5b) and 2-isopropylphenyl 2-methyl-5-nitrobenzenesulfonate (5e) showed a potent in vivo antifungal activity against Pyrcularia grisea, Phytophthora infestans and Sphaerotheca fusca.

High-k dielectrics like Ta2O5, TiO2 etc. should overcome high leakage current due to the low energy band-gap property for applying to the future DRAM device below 50nm design rule beyond. Various techniques including metal doping and bi-layer scheme were studied to improve the leakage current of I-V characteristics. The leakage current of Dy or Zr doped TiO2 could be improved depending on the doping concentration. Nb doping in Ta2O5 could increase the dielectric constant within the appropriate level of leakage current at the operation voltage. Bi-layer scheme of high-k dielectrics like HfO2-TiO2 or ZrO2-TiO2 also applied to reduce the leakage current with the high work function Ru electrode. Combination of high work function Ru as a top electrode with the bottom TiN electrode could reduce the leakage current by increasing band offset at the interface between the high-k and the electrode.

The fungicidal activities against phytopathogenic fungi of two aminothiazole compounds of N-[4-(4-fluoro)phenyl-2-aminothiazol-5-yl]pyrimidin-2-yl-N-subst. phenylamine (V-1, V-2) have been determined and these two compounds were used as the leading compounds in this study as V-1 for N-[4-(4-fluoro)phenyl-2-aminothiazol-5-yl]pyrimidin-2-yl-N-(3-hydroxymethyl)phenylamine and V-2 for N- [4-(4-fluoro)phenyl-2-aminothiazol-5-yl] pyrimidin-2-yl-N-3-(l-hydroxyethyl)phenylamine. Further syntheses of these two compounds, V-l and V-2, were conducted by reacting them with three functional groups, 2-(N-ethoxycarbonyl)piperidin-4-yl, 2-piperidin-4-yl, and 2-(N-methyl)-piperidin-4-yl-thiazole. From this scheme, 21 compounds were newly synthesized and their structures were confirmed by 1H-NMR-spectrum. The fungicidal activities of all the synthesized compounds against Phytophthora capsici were examined using the whole plant method. While the EC50 value of the commercial fungicide dimethomorph was 4.26 mM, that of IX-3g on P. capsici was 1.03 mM. Among the 21 chemicals, IX-3g showed the most potential antifungal activity in vivo. Therefore, IX-3g may be considered as a potential candidate for the control of phytopathogenic diseases characterized by P. capsici infection, and further studies will be conducted on the mode of action IX-3g.

This paper analyses the risk probability of an underwater tunnel excavation using an earth pressure balance (EPB) type tunnel boring machine (TBM). An event tree analysis (ETA) has been applied to quantify the risk at the preliminary design stage of the tunnel. Probable results, which may be sequenced from specific initiating events, are analyzed, and adequate general countermeasures (safety functions) are selected to ensure safety against risks. To identify the initiating events, various data on underwater tunneling such as empirical analyses; design reports; case studies of practical problems; numerical analyses and model test results; and hydrological analysis results were used. Event trees corresponding to three significant initiating events were constructed. Each event tree consists of five countermeasures that construct 32 paths, and the probability of each path is calculated. A quantitative risk assessment was performed and the occurrence probabilities and criticalities of the paths depending on the initiating events were considered. Based on these ETA results, it was found that the selected underwater tunnel site still has a considerable probability of accidents in spite of common countermeasures. Based on the evaluated risks, improved target probabilities are proposed to reduce the probability of disaster during construction. Additional countermeasures, in other words mitigation actions, corresponding to the new target are considered. As a result, technical risks and economical losses of property can be minimized in a systematic way. It was found that the ETA is an effective method for the evaluation and quantitative analysis of probable risks and for the proposition of countermeasures for hazardous environmental conditions such as the underwater tunnel.

Coenzyme $Q_{10}$ 과 그 유도체 coenzyme $Q_n$ 6종을 합성하고, 이들 유도체에 대하여 상피세포(LLC-PK1 cell)를 이용한 항산화 효과와 NIH/3T3 세포를 이용한 세포독성 실험을 실시하였다. 그 결과, 합성한 coenzyme $Q_n$ 유도체들이 coenzyme $Q_{10}$ 에 비해 우수한 항산화 효과를 나타내었으며, 그 중 coenzyme $Q_3$ -C가 모든 농도에서 $107.7{\sim}135.9%$ 로 가장 우수한 효과를 나타내었다. 또한, 모든 coenzyme $Q_n$ 유도체들이 Coenzyme $Q_{10}$ 과 유사한 세포독성을 나타내었다. Coenzyme $Q_n$ 의 n수에 따른 항산화 효과 및 세포독성 실험에서 isoprene unit의 수가 적은 유도체들에서 우수한 효과를 나타내었다. 【Coenzyme $Q_{10}$ and six derivatives of coenzyme $Q_n$ were synthesized and tested for their antioxidative effects occurred in proximal tubular epithelial cell (LLC-PK1 cell) and cytotoxicities using in NIH/3T3 cell. As the result, synthetic coenzyme $Q_n$ derivatives showed a potent antioxidative effect compared to coenzyme $Q_{10}$ . Among these synthetic compounds, coenzyme $Q_3$ -C at ranged 0.04 to 0.4 mmol showed the $107.7{\sim}135.9%$ of cell viability in LLC-PK1 cell. In the test of NIH/3T3, all synthesized coenzyme $Q_n$ derivatives showed the similar effect compared with coenzyme $Q_{10}$ . A correlation between isoprene unit number of coenzyme $Q_n$ derivatives and its biological effects, we suggest reduction of isoprene unit number of $Q_n$ derivatives may be related to the increase of antioxidants effects and the reduction of cytotoxicities.】

Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi 730-701, Korea(Received April 6, 2007)주제어: 보조효소 Qn, 이소피렌, p-하이드로퀴논Keywords: Coenzyme Qn, Isoprene, p-HydroquinoneCoenzyme Qn 유도체의 구조는 극성을 나타내는benzoquinone 머리 부분과 소수성인 polyprenyl 꼬리부분으로 이루어져 있다. Polyprenyl기에 포함된isoprene 단위에 의해 Coenzyme Qn으로 표시되며,여기서 n은 isoprene 단위의 수를 나타낸다. CoenzymeQn 유도체들 중에서 생체 내 가장 많이 존재하는 화합물은 n=10 이고 탄소수가 50개인 Coenzyme Q

When a tunnel is excavated underneath a groundwater table, groundwater flows into the tunnel and consequently, seepage forces act on the cross-section of the tunnel. Such seepage forces significantly affect the ground reaction curve, which is defined by the relationship between the internal pressure and displacement of the tunnel wall. From a practical point of view, a simplified analytical solution of the ground reaction curve accounting for the seepage forces with steady-state flow was developed in this study based on ground reaction curve theories from earlier studies. The simplified analytical solution derived in this study was validated by numerical analysis. The changes in the ground reaction curve according to various ground and groundwater table conditions were investigated. Finally, the simplified analytical solution of the ground reaction curve developed in this study can be used for approximate design of circular openings such as tunnels excavated underneath a groundwater table with seepage forces.

Pesticidal activities of 4-[5-(2-cyclopropylaminopyrimidin-4-yl)-4-(4-chloro-2-fluoro-phenyl)thiazol-2-yl]-1-methylpiperidine, designated as Comp I, have been determined against a mosquito larva,Culex pipiens pallens, and a phytopathogenic fungus,Phytophthora capsici. Comp I was used as the leading compound in this study. The compounds were synthesized by reacting them with two functional groups, 3-thiophenyl and 2-thiophenyl groups, instead of 4-chloro-2-fluorophenyl group in Comp I. Other functional groups such as 2-aminothiazole, 2-(1-methylpiperazin-4-yl)thiazole, and 2-(piperazin-4-yl)thiazole were also introduced instead of 2-methylpiperidin-4-yl-thiazole of Comp I. Compounds designated as XIII-6~XV-7 were newly synthesized and their structures were confirmed by1H- and13C-NMR spectroscopy. Mosquito larvicidal activities of all the synthesized compounds againstC. pipiens pallenswere examined and Comp I among them showed the strongest larvicidal activity as 0.513 mM of LC50value. The fungicidal activities of all the synthesized compounds againstP. capsiciwere examined using the whole plant method. Among the XIII-6~XV-7 chemicals, 5-(2-cyclopropylaminopyrimidin-4-yl)-4-(thiophen-2-yl)thiazol-2-amine (VIII-6) showed the most potent antifungal activityin vivo. While the EC50value of the commercial fungicide dimethomorph was 4.26 μM, EC50of VIII-6 was 0.94 μM. Therefore, thiazole derivatives can be considered as viable candidates for the control of mosquito larvae and plant diseases.

The liner of a pressure tunnel needs to be designed such that it can withstand the loads from the ground, the internal pressure, and minimize the development of significant pore pressures at the liner-ground interface. Pore pressures behind the liner reduce the effective stresses in the ground immediately in contact with the liner and can ultimately produce loss of support from the ground. Deformations and loads of the liner are intimately connected to the interplay that exists between liner, ground, and pore pressures in the ground. A closed-form analytical solution has been derived that accounts for the inter-relation between liner, ground, and pore pressures. Elastic response of the liner and ground, and plane strain conditions at any cross-section of the tunnel are assumed. The solution shows that stresses in the ground depend on the following dimensionless factors: relative stiffness of the ground and liner, ground Poisson’s ratio, surface slope angle, coefficient of earth pressure at rest, relative tunnel depth, and magnitude of the pore pressure behind the liner relative to the internal pressure. The minimum ground effective tangential stresses at the ground-liner interface increase with the relative stiffness of the liner, with the coefficient of earth pressure at rest, and with tunnel depth. They decrease with increasing surface slope angle and pore pressures behind the liner. As leakage through the liner increases, the pore pressures in the ground increase. This results in a decrease of effective radial and tangential stresses in the ground while displacements and loads of the liner are relatively less affected.

The primary support of a tunnel must be designed to sustain the loads that are transferred from the surrounding ground during excavation. The loads are originated from the ground itself and from the groundwater, if any. For deep circular tunnels, assuming that both ground and support remain within their elastic regime, the load on the primary support does not change with drainage conditions; it is the same whether there is flow towards the tunnel (drained tunnel) or the pore pressure behind the support is hydrostatic (no-drainage tunnel). Stresses and deformations in the ground, however, are quite different, with larger stresses and deformations occurring for the drainage case. In tunnels where there is an impermeable layer between the primary and secondary supports, as the secondary support is placed there is a load transfer from the primary to the secondary support. The primary support unloads and moves outwards, while the secondary support takes load and moves inwards. In tunnels where there is a drainage layer between the primary and secondary supports, the pressure behind the support depends on the discharge capacity of the drainage system relative to the water inflow from the ground. Within the range of cases investigated, the relative permeability factor, r0Kg/tfKf, can be used to evaluate the magnitude of the pore pressure build up behind the secondary support. Numerical experiments combined with analytical solutions provide a rational approach for a preliminary design of the primary and secondary supports in deep tunnels below the water table, and contribute to identify the load-transfer mechanisms between ground, water, and support. (A) "Reprinted with permission from Elsevier".

The magnitude and distribution of ground deformations around a tunnel are often monitored during construction and provide key information about ground-support interaction and ground behavior. Thus it is important to determine the effects of different parameters on ground deformations to accurately and effectively evaluate what contributes to ground and support behavior observed during excavation. This paper investigates one such relation: the effects of seepage on radial deformations. A number of numerical analyses have been conducted with the following assumptions: deep circular unsupported tunnel, elastic ground, isotropic far field stresses, dry ground or saturated ground with steady-state water seepage. The analyses cover a wide range of tunnel sizes, effective stresses, and pore pressures. Results from the numerical simulations confirm previous analytical solutions for normalized radial deformations behind the face (i.e. on the tunnel side of the face) of a tunnel excavated in dry ground, and have been used to propose a new analytical formulation for normalized radial displacements ahead and behind the tunnel face for both dry and saturated ground with water flow. Water seepage substantially increases the magnitude and distribution of the normalized radial deformations ahead of the face and at the tunnel face, but does not change much the displacement distribution behind the tunnel face.

Accurate estimation of geotechnical parameters is an important and difficult task in tunnel design and construction. Optimum evaluation of the geotechnical parameters have been carried out by the back-analysis method based on estimated absolute convergence data. In this study, a back-analysis technique using measured relative convergence in tunnelling is proposed. The extended Bayesian method (EBM), which combines the prior information with the field measurement data, is adopted and combined with the 3-dimensional finite element analysis to predict ground motion. By directly using the relative convergence as observation data in the EBM, we can exclude errors that arise in the estimation of absolute displacement from measured convergence, and can evaluate the geotechnical parameters with sufficient reliability. The proposed back-analysis technique is applied and validated by using the measured data from two tunnel sites in Korea. Copyright © 2005 John Wiley & Sons, Ltd.

Tunneling in difficult geological conditions is often inevitable especially in urban areas. Ground improvement and reinforcement techniques are required to guarantee safe tunnel excavations and/or to prevent damage to adjacent structures. The steel pipe-reinforced multi-step grouting method has been recently applied to tunnel sites as an auxiliary technique in Korea for impermeabilization in underwater tunnels as well as for reinforcement. However, this technique has been usually employed empirically without much understanding with regard to its effect on the tunnel safety. In this study, the face stability with steel pipe-reinforced multi-step grouting in underwater tunnels was evaluated by simultaneously considering two factors: one is the effective stress acting on the tunnel face calculated by limit theorem and limit equilibrium method; the other is the seepage force obtained by means of numerical analysis. This study revealed that the influence of the steel pipe-reinforced multi-step grouting on the support pressure required for the stability of the tunnel face in dry condition is not significant while there is relatively a significant reduction in seepage forces by adopting the technique in the underwater tunnel. The effect of permeability anisotropy on the seepage force acting on the tunnel face was also assessed by conducting a coupled analysis.

In this paper, the effect of seepage forces arising from the groundwater flow on the tunnel face stability was studied for underwater tunnels. The groundwater flow equation was solved and the seepage forces acting on the tunnel face were calculated using the upper bound solution in limit analysis. Especially, the effect of tunnel advance rate on the seepage forces and thus on the tunnel face stability was studied. A finite element program to analyze the groundwater flow around a tunnel with the consideration of tunnel advance rate was made. Example problem showed that the seepage force is greatly influenced by the tunnel advance rate in case of less permeable ground. Finally, a rational design methodology for the assessment of support pressures required for maintaining the stability of the tunnel face was suggested for underwater tunnels.

The effect of interfacial reactions at the poly Si1−xGex/HfO2 interface on the electrical properties of metal–oxide–semiconductor (MOS) capacitors with a poly Si1−xGex (x=0,0.6)/HfO2 gate stack was investigated relative to the deposition conditions for the poly Si1−xGex films, the Ge content of the poly Si1−xGex films, and the annealing temperatures, by the electrical measurements and x-ray photoelectron spectroscopy. With an increase in hydrogen induced from doping or from deposition gas used during the deposition of poly Si1−xGex (x=0,0.6) films, the accumulation capacitance of the MOS capacitors with a poly Si1−xGex/HfO2 gate stack became anomalous and the leakage current increased significantly, due to the formation of hydroxyl(OH–) ions or the partial reduction of HfO2 at the grain boundary. With an increase in Ge content of the poly Si1−xGex films, silicate formation became dominant at the poly Si1−xGex/HfO2 interface, resulting in a significant decrease in leakage current.

Recent years, as a rapid development of multimedia technology, video database system to retrieve video data efficiently seems to core technology in the oriented society. This thesis describes an efficient automatic frame detection and location method for content based retrieval of video. Frame extraction part is consist of incoming / outgoing car frame extraction and car number frame extraction stage. We gain star/end time of car video also car number frames. Frames are selected at fixed time interval from video and key frames are selected by color scale histogram and edge operation method. Car frame recognized can be searched by content based retrieval method.

Hafnium oxide (HfO 2 ) thin films were deposited by two different sputtering methods. In one case, hafnium (Hf) metal layer was pre-deposited before reactive sputtering process (method A), with the object of suppressing growth of the interfacial layer. Another one is conventional reactive sputtering, using DC magnetron in Ar+O 2 ambient (method B). Films made by method A showed thinner interlayer as well as good leakage current behavior, demonstrating that Hf pre-deposited layer can protect from incorporation of the oxidizing species. With high-temperature annealing, interfacial layer increases considerably, showing composition changes from silicate to SiO 2 (method A). In contrast, films by method B displayed little change in interlayer thickness since there exists previously thick SiO x bottom layer formed by O 2 stabilizing before reactive sputtering. Equivalent oxide thickness (EOT) of as-deposited and annealed HfO 2 films by method A is calculated to be ∼20 and ∼30 A, respectively, with allowable level of leakage current density.

Zirconium oxide thin films were deposited on p-type (1 0 0) silicon wafers by reactive d.c. magnetron sputtering. The as-deposited ZrO 2 films at the power of 300 W and at room temperature were amorphous and the ZrO 2 films became polycrystalline with both the monoclinic and tetragonal phases after post-annealing at 450 °C in N 2 ambient. The ZrO 2 films with Al electrode had the interfacial amorphous Al–O-containing layer, which was formed by their interaction, but the films with inactive electrodes such as Pt had no additional interfacial layer. The value of the capacitance equivalent thickness (CET) for ZrO 2 film with Al electrode was increased to about 12.4 A compared with the film with Pt electrode due to the additional interfacial layer between Al and ZrO 2 film. The difference of flat band voltage (Δ V FB ) between the films with two different electrodes was about 1.2 V because of their work function difference.

In this study, two factors are simultaneously considered for assessing tunnel face stability. The first is the effective stress acting on the tunnel face calculated by upper bound solution, and the other is the seepage force calculated by numerical analysis under the condition of steady-state groundwater flow. The seepage forces calculated by numerical analysis are compared with the results of a model test. The upper bound solution taking into consideration the seepage force acting on the tunnel face, shows that the minimum support pressure for the face stability is equal to the sum of the effective support pressure that is obtained from the upper bound solution based on effective stress and the seepage pressure acting on the tunnel face. It was found that the average seepage pressure acting on the tunnel face is proportional to the hydrostatic pressure at the same elevation, and the magnitude is about 22% of the hydrostatic pressure for the drainage type tunnel and about 28% for the waterproof type tunnel. The seepage forces obtained from the results of a model test showed similar trends as those calculated by numerical analysis.Key words: face stability, upper bound solution, seepage force, model test.

In this letter, a cost-effective vertical diode scheme for next-generation memory devices, including phase-change memories (PCMs), is realized. After the contact formation for diodes with only one mask layer, an amorphous silicon (a-Si) film was deposited within the contacts using SiH4 ramp-up ambient in a conventional batch-type furnace in order to minimize the growth of native oxide. A deposition/etch-back/deposition scheme enabled us to achieve robust vertical diodes without any seams or interfacial oxide layer within the vertical diode pillars. Subsequent annealing at 600 °C provided solid-phase epitaxial alignment of the a-Si layer. An ideality factor revealed that the new scheme provided noticeable crystallinity of the silicon diodes. Moreover, the electrical characteristics of the diodes verified that the scheme was suitable for full operation of PCM devices.

Hafnium oxide thin films were deposited on p-type (1 0 0) silicon wafers by reactive dc magnetron sputtering. Prior to the deposition of HfO2 films, a thin Hf film was deposited. Sputtered HfO2 thin films deposited at room temperature remain amorphous at T ° C and orthorhombic phases were observed above 650 °C. The monoclinic phase which is a stable HfO2 polymorphic form appeared after annealing above 800 °C. Capacitance equivalent thickness values decreased and leakage characteristics are improved by the Hf interlayer and O2 settlement process. The decrease of accumulation capacitance values upon annealing is due to the growth of an interfacial layer upon post-annealing. The flat band voltage (VFB) shifts negatively due to positive charge generated during post-annealing.

We first present chemical-vapor-deposited GeBiTe (CVD GBT) in a confined cell for high-performance phase-change random access memory (PRAM). Due to the fast crystallization of GBT, we were able to reduce the speed to less than 26 ns while maintaining endurance characteristics up to 109 cycles. Our results indicate that the scalable PRAM device enabling the use of PRAM in dynamic RAM and storage class memory applications can be realized using CVD GBT.

Needs for the performance improvement of memory subsystem in big data and clouding computing era begin to open new markets for emerging memories such as phase change memory, spin-torque-transfer magnetic memory, and metal oxide memory. To fulfill these needs, a cost-effective and high-speed phase change memory cell scheme was introduced at 19nm technology node, which is directly scalable down to 1y or 1z nm nodes and can be extendable to stacked array for higher density. Here, key technologies such as self-aligned cell patterning and vertical poly-Si diode switch on metal word line were adopted. In addition, damascene Ge-Sb-Te technologies were optimized to improve programming speed and to show excellent cell performances.

We investigated the evolution of microstructures and the #electrical properties of CeO 2 thin films deposited by the reactive DC magnetron sputtering method on the (100) silicon substrate upon annealing in the O 2 gas ambient. The CeO 2 thin films deposited at 300°C were polycrystalline. After annealing in ambient O 2 gas, the crystallinity of the CeO 2 film was improved and becomes more dense with annealing time and temperature. The maximum accumulation capacitance of CeO 2 thin film annealed above 700°C in the ambient O 2 gas decreased due to the growth of the interfacial SiO 2 layer between CeO 2 film and silicon substrate by the diffusion of oxidizing species through CeO 2 thin film from the ambient gas.

In this paper, the seepage force problems arising from the flow of groundwater into a tunnel were studied. Firstly, the effect of seepage forces acting on the tunnel lining was studied for the case of shallow drainage-type tunnels and these results were compared with the lining stresses developed for waterproof-type tunnels. This model was then reviewed through a comparison with an actual case study of the Seoul Subway Line No. 5. Secondly, the effect of seepage forces on the tunnel face stability was studied. In this study, two factors were considered simultaneously. The first factor considered was the effective stresses acting on the tunnel face, calculated from the upper bound solution of limit analysis and the other factor was the seepage forces, calculated from a numerical analysis under a steady-state of groundwater flow conditions. Consequently, reasonable design concepts applicable to the design of tunnel lining and to the evaluation of the support pressure required for maintaining the stability of the tunnel face were suggested for underwater tunnels.

The effect of interfacial reactions on the electrical properties of a polycrystalline (poly) Si1−xGex/HfO2 gate stack were evaluated in terms of annealing conditions and the results were compared with those of a conventional poly-Si/HfO2 system. In the poly-Si0.4Ge0.6/HfO2 gate stack, silicate formation was the dominant reaction at the poly-Si0.4Ge0.6/HfO2 interface after annealing at 900 °C, resulting in the significant decrease in leakage current. From x-ray photoelectron spectroscopy analysis, the binding states of Hf silicates were clearly observed at a binding energy of about 16.1 eV in Hf 4f spectra and 102.7 eV in Si 2p spectra. However, in the poly-Si/HfO2 gate stack, the accumulation capacitance became undeterminable and the leakage current increased suddenly after annealing at 900 °C due to silicide formation at the poly-Si/HfO2 interface. The differences in reactions between a poly-Si/HfO2 interface and a poly-Si0.4Ge0.6/HfO2 interface are attributed to the accumulation of Ge.

In this paper, current-voltage-temperature (I-V-T) characteristics of vertical diodes realized by different selective epitaxial growth techniques have been investigated. Diodes by the batch-type cyclic SEG process at low temperature have shown eligible performances for vertical switches, including ideality factor of 1.08, off-current of 1.0×10−12 A and on/off-ratio of 2.4×108. The optimization of crystallographic defects and series resistance is expected to be the most critical for the performances of vertical diodes for next generation memories.

Flowable CVD (Chemical Vapor Deposition) process having merits in terms of both superior gap-fill performance of SOD (Spin-on Dielectric) and process stability of CVD was introduced for the interlayer dielectric (ILD) in sub-20nm devices based on new concept and precursor. Remote plasma during low temperature deposition and ozone treatment was adopted to stabilize the film. We also developed a novel Flowable CVD process which does not oxidize Si or electrode, resulted in removal of Si 3 N 4 stopper layer as an oxidation or diffusion barrier. After the application of Flowable CVD to 20nm DRAM ILD, we could reduce not only loading capacitance of Bit-line by 15% but also enhance comparable productivity. Through the successful development of sub-20nm DRAM ILD Gap-fill process, Flowable CVD was successful demonstrated as a promising candidate for mass production-worthy ILD in sub-20nm next generation devices.

This paper discussed the key reliability issues for manufacturing high density phase change memory (PRAM). There are its own unique phenomena, such as resistance fluctuation, structural relaxation and crystallization, which are closely correlated with the device reliability characteristics, including data retention, cycling endurance, and write disturbance. Optimizing material composition and controlling doping concentration and minimizing variability of physical dimensions can improve the reliability issues. Above all, isotropic dimension scaling along with writing current scaling is essential for continuing scaling down below 20nm node.

Data retention characteristic is one of the most critical issues in low power DRAMs because it determines idle currents of self-refresh operation. Compared to normal healthy cells, a few ppm orders of cells in a tail distribution have much higher leakage currents. The origin of the leaky cells (so called weak cells or tail cells) has been quite arguable for the past decades [1, 2], but it should be scrutinized in order to achieve long data retention time. In this paper, we have thoroughly investigated the behavior of the retention weak cells using a newly generated combination program and TEM analysis so as to discover and explain their origins

This paper reviews recent progress and future outlook of PRAM as a promising candidate for emerging non-volatile memory. Electrical characteristics and reliability issues of PRAM with scale-down of the device dimension are discussed. Despite remarkable progress of PRAM properties in recent last decades, there are still several fundamental issues to resolve for broadening its application area. Several suggestions to overcome these property issues are introduced with recent experimental results.

We investigated the pressure dependence of the inductive coupled plasma (ICP) oxidation on the electrical characteristics of the thin oxide films. Activation energies and electron temperatures with different pressures were estimated. To demonstrate the pressure effect on the plasma oxide quality, simple N type metal-oxide-semiconductor (NMOS) transistors were fabricated and investigated in a few electrical properties. At higher pressure than 200mTorr, plasma oxide has a slightly higher on-current and a lower interfacial trap density. The on-current gain seems to be related to the field mobility increase and the lower defective interface to the electron temperature during oxidation.

A highly robust gap-fill process technology of spin-on glass (SOG) was developed for the interlayer dielectric (ILD) in sub-30nm devices. We revealed that the filling behavior of SOG within gaps during spin-coating is mainly dependent on the capillary effect. The highly wettable surface treatment prior to SOG coating was found to enhance the gap-fill performance remarkably. This technique plays a key role in maximizing capillary effect by raising surface wettability. The filling capability was also improved by optimization of baking temperature to minimize the viscosity of SOG. It was finally found that the defects of contact bridges due to poor filling of SOG were reduced to be almost free by those unique process refinements.