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In order to compare the corrosion resistance of conventional low carbon steel, Cu containing low carbon steel for sulfuric acid dew-point corrosion inhibition, and stainless 409L, immersion tests were carried out in 50 wt.% sulfuric acid. The effects of HCl concentraion on the corrosion behavior in a fixed sulfuric acid concentration (16.9 vol.%) was also investigated by immersion test. In addition to immersion test, field test in a thermal plant was carried out for 10 months. As a result, it was confirmed that Cu-containing dew-point corrosion resistent steel has the highest corrosion resistance compared with other materials. To verify superior corrosion resistence of dew-point corrosion resistant steel, surface morpology after various test was observed by SEM. It was found that surface corroded product of the dew-point corrosion resistant steel was much denser and thicker compared with the other steel.

It is hereby reported a simple, effective and sustainable method for the recovery of precious metals from end-of-life vehicle shredder residue and/or automobile shredder residue based on a hybrid ball-milling and microbubble froth flotation process. A ball-milling treatment of automobile shredder residue along a mixture of Fe/Ca/CaO nanoparticles had as main result the entrapment of precious metals and in subsidiary an improvement of the floatability of the various size fraction particles (1.0, 0.425, and 0.25 mm, respectively). Therefore, a separation of the settled fraction (poor in precious metals) and the floating fraction yielded a recovery of approximately 83–89% precious metals in the latter. Scanning electron microscopy-energy dispersive X-ray spectroscopy maps of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), Iridium (Ir), and copper (Cu) confirmed that result.

최근 대학 내 연구시설에서는 불안전한 상태, 불안전한 행동, 관리적 원인 등으로 인한 안전사고가 급증하고 있어 대학 내 연구시설의 체계적인 안전관리에 대한 필요성이 제기되고 있다. 현행 연구실 안전법에 의하면 안전교육은 과학기술분야 연구실에 초점을 맞추고 있으며, 교육의 내용 또한 전공 계열 실험⋅실습실의 특성 및 위험요소를 고려하지 못하고 있는 제약사항이 있다. 본 연구에서는 이러한 문제를 개선하기 위해 다양한 대학 전공계열을 아우를 수 있는 신 교육체계를 제시하였다. 이를 위해 전공 계열별 위험도 분석을 실시하여 상위 위험의 전공계열을 도출하였으며 위험도가 높은 전공계열에 대한 맞춤형 교육모듈을 제시하였다. 또한 실험특성에만 국한된 안전교육이 아닌 대학 전반의 환경보건안전(EHS)과 관련된 교육 모듈을 함께 도출하였다. 마지막으로 안전교육 모듈 별 교육 콘텐츠를 구성하기 위한 방안 및 교육과정 선정기준을 제시하였다.

A novel nanosize metallic calcium/iron dispersed reagent was synthesized and tested as coagulant/catalyst in a hybrid zero valent iron (ZVI)/H2O2 oxidation process to treat leachate. Two different ...

The separation of plastics containing brominated flame retardants (BFR) like (acrylonitrile-butadiene-styrene (ABS), high-impact polystyrene (HIPS), and polyvinyl chloride (PVC)) from automobile and electronic waste shredder residue (ASR/ESR) are a major concern for thermal recycling. In laboratory scale tests using a hybrid nano-Fe/Ca/CaO assisted ozonation treatment has been found to selectively hydrophilize the surface of ABS/HIPS and PVC plastics, enhancing ABS wettability and thereby promoting its separation from ASR/ESR by means of froth flotation. The water contact angles, of ABS/HIPS and PVC decreased, about 18.7°, 18.3°, and 17.9° in ASR and about 21.2°, 20.7°, and 20.0° in ESR respectively. SEM-EDS, FT-IR, and XPS analyses demonstrated a marked decrease in [Cl] and a significant increase in the number of hydrophilic groups, such as CO, CO, and (CO)O, on the PVC or ABS surface. Under froth flotation conditions at 50rpm, about 99.1% of combined fraction of ABS/HIPS in ASR samples and 99.6% of ABS/HIPS in ESR samples were separated as settled fraction. After separation, the purity of the recovered combined ABS/HIPS fraction was 96.5% and 97.6% in ASR and ESR samples respectively. Furthermore, at 150rpm a 100% PVC separation in the settled fraction, with 98% and 99% purity in ASR and ESR plastics, respectively. Total recovery of non-ABS/HIPS and PVC plastics reached nearly 100% in the floating fraction. Further, this process improved the quality of recycled ASR/ESR plastics by removing surface contaminants or impurities.

This study was conducted to examine the synthesis and application of novel nano-size calcium/iron-based composite material as an immobilizing and separation treatment of the heavy metals in fly ash from municipal solid waste incineration. After grinding with nano-Fe/Ca/CaO and with nano-Fe/Ca/CaO/[PO₄], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash). Heavy metals in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized, respectively. Additionally, scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDS) observations indicate that the main fraction of enclosed/bound materials on treated fly ash includes Ca/PO₄-associated crystalline complexes. After nano-Fe/Ca/CaO/[PO₄] treatment, the heavy metal concentrations in the fly ash leachate were much lower than the Japan standard regulatory limit for hazardous waste landfills. These results appear to be extremely promising. The addition of a nano-Fe/Ca/CaO/PO₄mixture with simple grinding technique is potentially applicable for the remediation and volume reduction of fly ash contaminated by heavy metals.After grinding with nano-Fe/Ca/CaO and nano-Fe/Ca/CaO/[PO₄], approximately 30 wt% and 25 wt% of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lowest weight of the magnetically separated fly ash fraction (i.e., 91% in 25% of treated fly ash), whereas heavy metals either in the magnetic or nonmagnetic fly ash fractions were about 98% and 100% immobilized. These results appear to be very promising, and the addition of nano-Fe/Ca/CaO/PO₄mixture with simple grinding technique may be considered potentially applicable for the remediation and volume reduction of contaminated fly ash by heavy metals.

We are motivated by both the accumulating evidence for the connection of solar variability to the chemistry of nitrogen oxide in the atmosphere and recent finding that the Galactic cosmic-ray (GCR) influx is associated with the solar northsouth asymmetry. We have analyzed the measured pH in precipitation over the 109 stations distributed in the United States. We have found that data of pH in precipitation as a whole appear to be marginally anti-correlated with the solar asymmetry. That is, rain seems to become less acidic when the southern hemisphere of the Sun is more active. The acidity of rain is also found to be correlated with the atmospheric temperature, while not to be correlated with solar activity itself. We have carried on the analysis with two subsamples in which stations located in the east and in the west. We find that the pH data derived from the eastern stations which are possibly polluted by sulfur oxides and nitrogen oxides are not correlated with the solar asymmetry, but with the temperature. On the contrary, the pH data obtained from the western stations are found to be marginally anti-correlated with the solar asymmetry. In addition, the pH data obtained from the western stations are found to be correlated with the solar UV radiation. We conclude by briefly pointing out that a role of the solar asymmetry in the process of acidification of rain is to be further examined particularly when the level of pollution by sulfur oxides and nitrogen oxides is low.

Due to requiring higher water quality standards over time, new technologies are being employed for wastewater treatment. Dissolved air flotation (DAF) and membrane bioreactor (MBR) technologies are widely employed as new technologies in wastewater treatment. DAF is used due to its excellent separation capability of suspended solids as well as oily material. MBR is used because it may provide a high level of mixed liquor suspended solids in a biological system and excellent separation capability too. In the investigation, separation by DAF, without addition of coagulant, could remove chemical oxygen demand by potassium dicromate (COD cr ) up to over 70%, biochemical oxygen demand (BOD 5 ) 73%, suspended solids (SS) 83%, total nitrogen (T-N) 55%, and total phosphorus (T-P) 65% in influent of municipal wastewater. Average overall removal rates of water quality parameters by the DAF-MBR system were very high such as COD cr 95.9%, BOD 5 99.7%, chemical oxygen demand by potassium permanganate) 93.6%, T-N 69.8%, NH 4 -N 98.5%, T-P 78.2%, and SS 99.5%, which satisfy effluent water quality standards. Membrane separation in the MBR system produced a very low SS concentration of 1.27 mg/l in the final effluent. It was proven that DAF separation is an excellent technology for pretreatment of wastewater treatment, especially for an MBR system.

Membrane Bioreactor (MBR) process is increasingly being used as a more advanced technology for biological wastewater treatment. However, due to membrane fouling, MBR system is often restricted in field application. Membrane fouling in MBR system may cause high maintenance cost, and reduction in membrane’s lifespan. Membrane fouling reduction in MBR system was investigated using ozone in the study. Ozone is being employed in wastewater treatment, and it may change microbial characteristics in MBR system by changing the water environment to more oxidative one. Experimental results of this work were analyzed with respect to various parameters, such as BOD5, CODCr, Total Nitrogen (TN), Total Phosphorus (TP), Extracellular Polymeric Substances (EPS) production, tensile strength, Sludge Volume Index (SVI), Oxidation Reduction Potential (ORP), field emission scanning electron microscope (FE-SEM) photos, and permeability or effluent flow rate of membrane. MBR system applied with ozone injection in aeration tank showed high performance in removing water quality parameters such as BOD5, CODCr, TN, and TP. Especially removal of TP was remarkably enhanced from about 45% to 87% by ozone dosage. Before ozone dose, backwash was needed once in every two weeks. However after the ozone injection, backwash was not required for more than 4 months. When the MBR system was in operation for two weeks, membrane was in need of a backwash. However, permeability of the used membrane has gradually recovered to the level of backwashed state, and maintained the same permeability rate thereafter.

Algae blooms have soared recently in the lakes across the nation due to eutrophication. Blue-green algae cause un-pleasant scene, produce taste and odor problem, and hinder processes in drinking water treatment. Algae toxicity monitoring has been strengthened, because the damages of wild lives and livestocks by algal toxins have been reported. Investigation on the cha-racteristics of cyanobacterial occurrence and concentration distribution of Cyanotoxins in Hoeya reservoir have been conducted. Physical and chemical influences of water environment on cyanobacterial occurrences have also been studied. Movements of four species of Microcystin and five species of Anatoxin-a among Cyanotoxins were observed by LC-MS/MS analysis. Microcystis spp. among the cyanobacteria have mainly dominated in the Hoeya reservoir during the investigating period. The density of cyano-bacteria were positively correlated with temperature and pH of water. Highest concentrations of Microcystin-LR and Microcystin- RR were 0.424 µg/L and 0.117 µg/L at the sampling points. Total concentration of Cyanotoxins in water coming into the water treatment plant was 0.182 µg/L, and they were not detected in treated water.

Current principles of designating a smoking area within a non-smoking area rely on mere compartmentalization. This causes non-smokers aversion against smokers and smokers complaints about anti-smoking policies, which means both of them are not satisfied with the current scheme. In addition, such a system, far from the original intent of the law, does not provide appropriate respect for people`s rights. The biggest problem of the current scheme is that smoking areas are not separated from non-smoking areas. Japan has continued installing independent smoking areas since 2002 and witnessed a decrease in the smoking rate. The country`s success is attributable to: the state`s active intervention in connection with enterprises; continuous environmental improvements and creation of goods; `smoking etiquette` campaigns; and the sociality and group consciousness of Japanese people. It is recognized that the synergy of the designation of independent smoking areas and such multi-faceted efforts has led to the nation`s accomplishment. Hence, it is required to install independent smoking areas in non-smoking areas in Seoul in order to respect the rights of smokers and non-smokers and resolve conflicts between them. It is not suitable to merely model after Japan`s case, however, studies and guidelines that are tailored to Korea`s own environment and social atmosphere are required. To ensure that the people recognize the necessity for smoking areas, a social consensus is formed and proper smoking areas are established in a systemic manner, a system for that purpose should connote a symbol of the social consensus and consequent guidelines should take physical elements, human activities and semantic assignment into consideration. This study aims to present basic guidelines to install separated smoking areas, which will keep distance between smokers and non-smokers, form a social consensus and establish a sound smoking culture. These would ensure that the rights of both smokers and non-smokers are fully respected and that government policies are trusted by the people.

A novel nanosize metallic calcium/iron dispersed reagent was synthesized and tested as coagulant/catalyst in a hybrid zero valent iron (ZVI)/HConventional treatments (biological or physicochemical) are not sufficient anymore to reach the level of purification needed to fully reduce the negative impact of landfill leachates on the environment. This implies that new treatment alternatives species must be proposed. A coupled zero valent iron (ZVI)/H

One method of weakening the inherently hydrophobic surface of plastics relevant to flotation separation is heterogeneous nano-Fe/Ca/CaO catalytic ozonation. Nano-Fe/Ca/CaO-catalyzed ozonation for 15 min efficiently decreases the surface hydrophobicity of brominated and chlorinated flame retardant (B/CFR)-containing plastics (such as acrylonitrile-butadienestyrene (ABS), high-impact polystyrene (HIPS), and polyvinyl chloride (PVC)) in automobile shredder residue (ASR) to such an extent that their flotation ability is entirely depressed. Such a hydrophilization treatment also stimulates the ABS, HIPS, and PVC surface roughness, wetting of the surface, and the thermodynamic equilibrium conditions at the surface and ultimately changes surface polarity. SEM-EDS, AFM, and XPS analyses of the PVC and ABS surfaces demonstrated a marked decrease in [Cl/Br] and a significant increase in the number of hydrophilic groups, such as C-O, C=O, and (C=O)-O. Under froth flotation conditions at 50 rpm, about 99.5 % of ABS and 99.5 % of HIPS in ASR samples settled out, resulting in a purity of 98 and 98.5 % for ABS and HIPS in ASR samples, respectively. Furthermore, at 150 rpm, we also obtained 100 % PVC separation in the settled fraction, with 98 % purity in ASR. Total recovery of non-B/CFR-containing plastics reached nearly 100 % in the floating fraction. The amount of nano-Fe/Ca/CaO reagent employed during ozonation is very small, and additional removal of surface contaminants from the recycled ASR plastic surfaces by ozonation makes the developed process simpler, greener, and more effective.

Within the semiconductor lithographic process, alignment control is one of the most critical considerations. In order to realize high device performance, semiconductor technology is approaching the 10 nm design rule, which requires progressively smaller overlay budgets. Simultaneously, structures are expanding in the 3rd dimension, thereby increasing the potential for inter-layer distortion. For these reasons, device patterning is becoming increasingly difficult as the portion of the overlay budget attributed to process-induced variation increases. After lithography, overlay gives valuable feedback to the lithography tool; however overlay measurements typically have limited density, especially at the wafer edge, due to throughput considerations. Moreover, since overlay is measured after lithography, it can only react to, but not predict the process-induced overlay. This study is a joint investigation in a high-volume manufacturing environment of the portion of overlay associated with displacement induced by a single process across many chambers. Displacement measurements are measured by Coherent Gradient Sensing (CGS) interferometry, which generates high-density displacement maps (>3 million points on a 300 mm wafer) such that the stresses induced die-by-die and process-by-process can be tracked in detail. The results indicate the relationship between displacement and overlay shows the ability to forecast overlay values before the lithographic process. Details of the correlation including overlay/displacement range, and lot-to-lot displacement variability are considered.

Simultaneous immobilization of heavy metals and decomposition of halogenated organic compounds in different fractions of automobile shredder residue (ASR) were achieved with a nano-sized metallic calcium through a 60-min ball milling treatment. Heavy metal (HM) immobilization and chlorinated/brominated compound (CBC) decomposition efficiencies both reached 90-100 %, after ball milling with nanometallic calcium/calcium oxide (Ca/CaO) dispersion, regardless of ASR particle size (1.0, 0.45-1.0, and 0.250 mm). Concentrations of leachable HMs substantially decreased to a level lower than the regulatory standard limits (Co and Cd 0.3 mg L-1; Cr 1.5 mg L-1; Fe, Pb, and Zn 3.0 mg L-1; Mn and Ni 1 mg L-1) proposed by the Korean hazardous waste elution standard regulatory threshold. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) element maps/spectra showed that while the amounts of HMs and CBCs detectable in ASR significantly decreased, the calcium mass percentage increased. X-ray powder diffraction (XRD) patterns indicate that the main fraction of enclosed/bound materials on ASR includes Ca-associated crystalline complexes that remarkably inhibit HM desorption and simultaneously transform dangerous CBCs into harmless compounds. The use of a nanometallic Ca/CaO mixture in a mechanochemical process to treat hazardous ASR (dry conditions) is an innovative approach to remediate cross-contaminated residues with heavy metals and halogenated compounds.

Phosphorus removal during discharge of wastewater is required to achieve in a very high level because eutrophication occurs even at a very low phosphorus concentration. However, there are limitations in the traditional technologies in the removal of phosphorus at very low concentration, such as at a level lower than 0.1 mg/L. Through a series of experiments, a possible technology which can remove phosphate to a very low level in the final effluent of wastewater was suggested. At first Al, Zn, Ca, Fe, and Mg were exposed to phosphate solution by impregnating them on the surface of activated alumina to select the material which has the highest affinity to phosphate. Ki- netic tests and isotherm tests on phosphate solution have been performed on four media, which are Ca-impregnated activated alumina, activated alumina, Ca-impregnated loess ball, and loess ball. Results showed that Ca-impregnated activated alumina has the highest capacity to adsorb phosphate in water. Scanning electron microscope image analysis showed that activated alumina has high void volume, which provides a large surface area for phosphate to be adsorbed. Through a continuous column test of the Ca-impregnated activated alumina it was discovered that about 4,000 bed volumes of wastewater with about 0.2 mg/L of phosphate can be treated down to lower than 0.14 mg/L of concentration.

Journal of Korean Society of Water and Wastewater Vol. 26, No. 5, pp. 713-721, October, 2012 상하수도학회지, 논문 26권 5호, pp.713-721, 10월, 2012 Phosphorus Removal in Wastewater Using Activated Ca-Loess Complex Seong Chul Kang·Byoung Ho Lee * Civil and Environmental Engineering, University of Ulsan, Ulsan City 680-749, Korea(2012년 8월16일 접수; 2012년 10월12일 수정; 2012년 10월15일 채택) In many instances phosphorus is a limiting factor for eutrophication in streams, and lakes. Because wastewater treatment plant itself may be the main phosphorus source in a natural water body, removal of phosphorus in final effluent of wastewater treatment processes is required. Amongst various technologies for phosphorus removal in wastewater, adsorption technology was investigated using activated Ca-loess complex. Ca was added in loess to enhance adsorption capacity and intensity of phosphorus. Ca added loess was activated at a high temperature of 400 ℃ which turned out to be the optimum temperature. Activated Ca-loess complex below 400 ℃ had not enough strength to be applied as an activated Ca-loess pallet column in wastewater treatment process. Ca-loess complex which activated above 400 ℃ lost its adsorption capacity as the loess surface was glassified when the activation tem-perature reached above 400 ℃. Even if adsorption capacity of activated Ca-loess was not very high due to the lack of abundant pores on its surface, adsorption intensity was still high because it was activated with added Ca in loess. Activated loess was made by pallets. The activated loess pallets were filled in a column, and were applied in wastewater treatment process. Using an activated Ca-loess pallet column, total phosphorus (T-P) was reduced from about 0.5 mg/l to lower than 0.1 mg/l in wastewater treatment, and ionic phosphorus (phosphate) was completely removed for the four months of pilot plant operation.Key words : phosphorus, loess, activation, Ca, phosphate *Corresponding author : E-mail : bhlee@ulsan.ac.kr(B. H. Lee) 강이나 호수로 유입되는 인(P)이 종종 부영양화의 가장 큰 제한요소로 작용한다. 그런데 하수처리장의 방류수가 자연수계에 인의 중요한 공급처로 작용하는 경우가 많기 때문에 하수처리장의 최종 처리수에서 인의 제거가 요구된다. 하수에서 인을 제거할 수 있는 많은 기술 중에서, 활성 칼슘-황토의 복합체를 이용한 흡착기술을 연구하였다. 칼슘을 황토에 첨가하여 인의 흡착 용량과 흡착강도를 증가시켰다. 칼슘을 첨가한 황토를 최적 온도로 밝혀진 400 ℃의 고온에서 활성화시켰다. 400 ℃ 미만에서 활성화시킨 칼슘-황토는 하수처리 공정의 활성칼슘-황토 복합체를 이용한 처리조에 적용하기엔 강도가 부족하였다. 반면 400 ℃ 초과 온도에서 활성화시킨 칼슘-황토 복합체는 복합체 표면이 유리화되어 흡착용량이 감소하였다. 활성칼슘-황토 복합체는 표면에 충분한 기공이 발달하지 못하여 인의 흡착용량에 한계는 있으나 칼슘을 첨가하였기 때문에 흡착강도는 높았다. 활성칼슘-황토는 입자형 복합체로 만들어졌다. 제조된 복합체를 흡착칼럼에 채워 하수처리공정에 적용하였다. 활성칼슘-황토의 복합체를 충진한 칼럼을 파일롯트 플랜트에 적용한 결과 0.5 mg/l의 인의 농도를 0.1 mg/l로 낮출 수 있었고, 이온성 인을 4개월의 운전기간 동안 완전하게 흡착시켜 제거할 수 있었다.주제어 : 인, 활성, 황토, 칼슘, 이온성 인

The purpose of Crash Protected Module in Black Box used at aircraft is to protect a stored information(Flight data & Cockpit Voice) safely even after extreme environment like a plane crash. This study shows the structure & thermal analyses and the comparisons of predictions and results of tests about CPM for Crash Survival through extreme environment such as Penetration Resistance, High Temperature Fire, Low Temperature Fire. Specially, the Effect of housing thickness change was studied through the Penetration Resistance analysis using LS-DYNA, and the influence of volume ratio change between phase change material and thermal insulation material was studied through the High Temperature & Low Temperature analysis using Icepak. Also, structural and thermal reliability of CPM was validated through the tests.

In this study, three pilot-scale plants with the capacity 30 m 3 /day were designed and set up to treat reservoir water for the production of drinking water. Three treatment processes were compared in the pilot testing: process 1 (coagulation- flocculation- sedimentation- sand filtration- ozone- BAC); process 2 (coagulation- flocculation- sedimentation- microfiltration-ozone- BAC); and process 3 (coagula - tion- flocculation- sedimentation- sand filtration- GAC). The quality of water has been evaluated on the basis of selected parameters such as turbidity, color, consumption of KMnO4, dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), geos- min and 2-MIB. A detailed assessment of performance was carried out during a five months operation. Process 2 was found to have better removal efficiency of DOC, THMFP, geosmin and 2-MIB than process 1 and process 3 under identical conditions, although the removal rate of color was found to be the same in the three cases.

This study investigates the treatment of pigment wastewater using a sequential batch reactor (SBR) followed by dissolved ozone flotation-pressurized ozone oxidation treatement (DOF-PO 2 ). The process efficiency has been evaluated at the lab scale on the basis of water quality parameters. In addition, the effect of pure oxygen and air was investigated on the removal of COD, BOD, and TN in the SBR process. It was observed that under comparable conditions the removal efficiencies of these water quality parameters using pure oxy - gen and air were similar. The effect of the recycle rate was also investigated for its impact on the water quality parameters using different ozone dissolving pressures in a DOF process in order to optimise conditions. The results conclude that the use of an SBR and ozone contact by DOF-PO2 is a highly effective treatment for pigment wastewater and aids in the achievement of effluent discharge criteria.

The feasibility and industrial potential of using bio-flours from tropical crop residues, in particular starch containing bio-flours, for the manufacture of bio-composites was investigated. Polypropylene (PP) and poly(butylene succinate) (PBS) were compounded with bio-flours from pineapple skin (P) and from non-destarched (CS) and destarched (C) cassava root by twin-screw extrusion. In CS composites, two levels of starch granules melting were achieved by adjusting the extrusion temperature, enabling control of morphological and mechanical properties. The use of bio-flours reduced tensile strength by 26-48% and impact strength by 14-40% when the proportion of bio-flour was increased to 40% w/w, while flexural strength initially increased upon addition of bio-flours, before decreasing at higher loads. The use of compatibilizers, in particular maleic anhydride-polypropylene (MAPP) in PP composites with 30% bio-flour resulted in tensile strength similar to non-compatibilized composites with 10% bio-flour (34-35?MPa). MAPP also increased flexural strength to higher levels than pure PP, resulting in a stronger, but less flexible material.

The grain boundary segregation of boron atoms in high strength low alloy steels containing 50 ppm boron was accomplished using atom probe tomography (APT) and nano-beam secondary ion mass spectroscopy (SIMS). The formation of boro-carbides under an excessive addition of boron to the steels was identified through the SIMS and TEM. The APT was performed in order to evaluate the composition of the alloying elements, such as, boron and carbon, segregated at prior austenite grain boundaries. The boron contents at the prior austenite grain boundaries were approximately 1.7 ± 0.2 at.%, which was approximately 70 times more than the amount of boron added to the steels.

The purpose of VDR capsule is to maintain a stored information securely and retrievably in the extreme environment like voyage incident. This study shows the modellings, the analyses and the experiments of the survivabili ty test of penetration, high and low temperature fire. The capsule housing is used to protect capsule against penetration and the influences of its thickness are studied by the modelling and analysis of penetration using LS-DYNA. The phase change materia l and thermal insulation material are used to protect capsule against high an d low temperature fire test. The thermal characteristics of various volume ratios of p hase change material to thermal insulation material were conducted. Also the tests wer e conducted to confirm the structural and thermal reliability. Key words: Voyage data recorder, Capsule (Crash Protected-memory Module), Crash survivability test †교신저자(LIG넥스원 기계연구센터, E-mail:bhleebe@lignex1.com, Tel: 031-288-9222)1 LIG넥스원 기계연구센터 1. 서 론 항해자료기록기(VDR, Voyage Data Recorder)는 항해데이터, 엔진의 상태, 운항정보, 기상정보 등의 정보를 저장하여 해상사고 시 사고분석을 위하여 사용된다. 동일한 해난사고예방을 위하여 Solar 5장에 정의된 선박에 설치하게 되어 있다. 특히 본 논문에서 다루고 있는 캡슐은 해양사고와 같은 극한환경에서도 저장된 정보를 안전하고 재생가능하게 보존하는 기능을 담당하는 구성품이다. 국내의 개발현황은 LIG넥스원에서 2006년에 소형 항공기용 블랙박스를 처음 개발하여, 2009년에 KUH헬기에 탑재하였으며, 현재 무인항공기용 블

The effect of initial texture on the anisotropic properties of AZ31 Mg alloys was investigated on the basis of microstructure evolution after compression tests and Lankford parameter ( r -value) experiments at various temperatures. Two kinds of sheets were used: one is the cast-and-rolled sheet, and the other is the strip-cast sheet. Compression tests were conducted up to a strain of 0.3 at temperatures of 200–400 °C, and tensile tests were performed to obtain the r -value at various temperatures (25–450 °C). The results showed that, at all test temperatures, the average r -value of the RD plane were greater than those of the ND and TD planes in the cast-and-rolled material. When comparing the average r -value of the RD plane, the cast-and-rolled material revealed much higher values than those of strip-cast material. It was observed that the cross-sectional shape of RD compressive specimens (the compression axis was parallel to the rolling direction) of cast-and-rolled materials changed from an initial circular shape to an ellipsoidal shape due to the plastic anisotropy. Compression processes of specimens were simulated using a finite element method where the Hill's anisotropic yield criterion was adopted. The simulated results were in a good agreement with experimental data.

Fatigue characteristics of rolled Mg–3Al–1Zn (AZ31) alloy were investigated by performing the low-cycle fatigue test along the rolling direction. The alloy was found to have a strong basal texture so that the fatigue deformation was predominated by the alternation of twinning and detwinning during each cycle, and this made the cyclic stress response unstable and introduced a non-zero mean stress and/or strain depending on the loading condition. An energy-based concept was successfully used to predict the low-cycle fatigue life because a plastic strain energy density was found to have good characteristics as a fatigue parameter; it was stabilized at the early stage of fatigue life and nearly invariant through entire life. In the life prediction model, the effect of mean stress was appropriately considered.

Acid dew point corrosion is a common phenomenon for industrial equipments such as duct, stack, gas gas heater (GGH) in plants using fossil fuels. During the burning process, sulfur in fossil fuel is oxidized to produce sulfuric dioxide (SO2) and further oxidized to sulfuric trioxide (SO3). Under the dew point temperature, water drops form on the surface of equipments along with sulfuric trioxide to develop sulfuric acid (H2O+SO3àH2SO4). Sulfuric acid causes severe damages to equipments and special steel products that are strong against acid dew point corrosion are on the market in the form of cold rolled (CR) or hot rolled (HR) steel. Although these products have stronger corrosion resistance than normal steel to sulfuric acid, life span is still short and further increase of corrosion resistance is required. In this research, we applied thin coating layer to steel and studied how corrosion resistance is changed. Concentration of sulfuric acid on steel equipments is varied according to temperature. A couple of test coupons with 38 mm diameter were immersed in controlled sulfuric acid solutions and weight differences were measured before and after corrosion test. Different types of coatings were applied and tested. Inorganic type coating seems to provide efficient protection against sulfuric acid corrosion but localized corrosion occurrs. We propose a possible solution for localized corrosion as well. Bar coating was used to prepare coating steels and spark erosion was used to make coin type test coupons. Coating layers were observed by various analytical tools including FT-IR, SEM, EPMA, GDS etc.

The influence of stress state on the high temperature workability of rolled AZ31 Mg alloy was investigated on the basis of a processing map. To construct the processing map, high temperature compression tests were carried out on samples oriented parallel to the rolling direction at various temperatures (25 °C∼450 °C) and strain rates (10−3 s−1∼5s−1), and then the results were compared with those of a torsion test. The overall efficiency profiles of both the compression and torsion processing maps were similar to each other, but the index of dissipation efficiency in the torsion was somewhat lower than that in the compression. The microstructure of the compressed specimens revealed much finer grained structure than that of the torsion specimens. Such microstructural differences were attributed to the different tendencies of twin formation and texture evolution depending on the stress state.

It has been widely reported that carbide-free bainitic steels or super-bainite TRIP (SB-TRIP) steels for the automotive industry are a new family of steels offering a unique combination of high strength and ductility. Hence, it is important to exactly evaluate the volume fraction of RA and to identify the 3-D morphology of constituent phases, because it plays a crucial role in mechanical properties. Recently, as electron back-scattered diffraction (EBSD) equipped with focused ion beam (FIB) has been developed, 3-D EBSD technique for materials science are used to these steels. Moreover, newly developed atom probe tomography (APT) technique can provide the exact distribution and chemical concentration of alloying elements in a sub-nm scale. The APT analysis results indicate exactly the distribution and composition of alloying elements in the austenite and bainite phases of SB-TRIP steels with the atomic-scale resolution. And thus, no partitioning of aluminum and manganese atoms was showed between the austenite containing at% C and the bainitic ferrite associated with at% C in SB-TRIP steel.

This study aimed to elucidate the deformation mechanism during low-temperature superplasticity of fine-grained Ti- 6Al-2Sn-4Zr-2Mo-0.1Si alloy in the context of constitutive equation. For this purpose, initial coarse equiaxed microstructure was refined to 2.2μm via dynamic globularization. Globularized microstructure exhibited large superplastic elongations(434-826%) at temperatures of 650-750 o C and strain rate of 10 -4 s -1 . It was found that the main deformation mechanism of fine-grained material was grain boundary sliding accommodated by dislocation motion with both stress exponent (n) and grain size exponent (p) values of 2. When the alpha grain size, not sub-grain size, was considered to be an effective grain size, the apparent activation energy for low-temperature superplasticity of the present alloy(169kJ/mol) was closed to that of Ti-6Al-4V alloy(160kJ/mol).

The Dissolved Air Flotation (DAF) process is very effective in removing low density floc particles for drinking water treatment. It is especially well known in removing turbidity and algae by flotation process. The micro-bubbles in the DAF process pick up small flocs, thereby turbidity materials and floated algae are removed efficiently. When air is substituted by ozone in the DAF process, the removal rates of water quality parameters are highly enhanced including turbidity and algae. The turbidity removal rate is enhanced by 1.1% while the removal rate of THMFP is increased by 11.7%. Other parameters such as TOC, and microbial agents are also removed greatly by using ozone instead of air in DAF system.

Fatigue behavior of rolled AZ31 magnesium alloy, which shows an anisotropic deformation behavior due to the direction dependent formation of deformation twins, was investigated by carrying out stress and strain controlled fatigue tests. The anisotropy in deformation behavior introduced asymmetric stress-strain hysteresis hoops, which make it difficult to use common fatigue life prediction models, such as stress and strain-based models, and induced mean stress and/or strain even under fully-reversed conditions; the tensile mean stress and strain were found to have a harmful effect on the fatigue resistance. An energy-based model was used to describe the fatigue life behavior as strain energy density was stabilized at the early stage of fatigue life and nearly invariant through entire life. To account for the mean stress and strain effects, an elastic energy related to the mean stress and a plastic strain energy consumed by the mean strain were appropriately considered in the model. The results showed that there is good agreement between the prediction and the experimental data.

Owing to the strong oxidation potential, ozone has been used widely in advanced water treatment. However, degradation and oxidation efficiencies of NOM (Natural Organic Matter) by the traditional ozone contact system are normally believed to be low. Oxidation efficiency of NOM by the PHOC (Pressurized High Ozone Contact) method was compared with that by the MOC (Mechanical Ozone Contact, the traditional system) method for the drinking water treatment. Sand filtered water of the drinking water treatment plant was used for experimental samples. Removal rates of UV254 absorbance, KMnO4 consumption and DOC by the MOC system were 18.4%, 2.39%, and 2.72% respectively with 1 mg-O3/L. On the other hand, removal rates of KMnO4 consumption, TOC, DOC, UV254 absorbance and SUVA by the PHOC system were 8–20%, 7.52–34.4%, 6.65–18.2%, 37.4–60.8% and 33.8–60% with 1–3 mg/L of ozone concentrations. Concentration of BDOC after ozone application was 0.003–0.044 mg/L by the MOC method, while 0.084–0.044 mg/L by the PHOC method with 1–3 mg/L of ozone concentrations. Concerning molecular weight distribution, fractions of NOM below 1 kDa were increased by the PHOC method of ozone application. Analysis shows that the reason for overall enhancement of the treatment efficiencies by the PHOC system is because contacting surface area of numerous micro ozone bubbles was increased dramatically in the PHOC system, and oxidation potential was enhanced by increased ozone concentrations in the ozone contact tank. Thus, it is understood that the PHOC method is a more efficient system for ozone application than the traditional MOC system in drinking water treatment process.

In this study, dissolved ozone flotation and conventional mechanical diffuser ozonation systems have been applied to treat the downstream municipal wastewater. The process efficiency has been evaluated in the lab bench scale on the basis of the removal rate of some wastewater quality parameters, like turbidity, SS, color, UV254, COD, BOD, T-N, T-P and bacteria. DOF is found to be an efficient ozonation technique in comparison to the mechanical diffuser system under identical conditions, though the removal efficiencies of coliform bacteria are found to be the same in both cases. The optimum ozone dose of 6.1 mg/L is found in the DOF system. As for the result of this investigation, a DOF pilot plant with the capacity of 200 m3/d was designed and set up to treat the effluence of secondary wastewater, and detailed assessment of performance was carried out during one month operation. The results indicate a good removal rate of 86.9% turbidity, 81% TSS, 72.6% color, 82.4% BOD and 92% total phosphorus. However, lower removal efficiencies of 42.9% and 33.4% were obtained for COD and T-N respectively. Almost 100% disinfection efficiency was achieved by removing heterotrophic and coliform bacteria. DOF technology is very effective and economically viable for municipal wastewater treatment in the present day context.

In this study, optimum processing condition of rolled AZ31 Mg alloy was investigated by utilizing processing map and constitutive equation considering microstructure evolution(dynamic recrystallization) occurring during hot-working. A series of mechanical tests were conducted at various temperatures and strain rates to construct a processing map and to formulate the recrystallization kinetics in terms of grain size. Dynamic recrystallization(DRX) was observed to occur at a domain of and 1/s(maximum dissipation-efficiency region). The effect of DRX kinetics on microstructure evolution was implemented in a commercial FEM code followed by remapping of the state variables. The volume fraction and grain size of deformed part were predicted using a modified FEM code and were compared with those of actual hot forged part. A good agreement was observed between the experimented results and predicted ones.

In this study, the effects of initial texture on the twinning formation of AZ31 Mg rolled sheet was investigated. Uniaxial compression tests were carried out on samples cut along the normal direction(ND) and roiling direction(RD), respectively, of rolled AZ31 Mg alloy sheet at various temperatures (RT, 200, 250, 300, 350, ) with the fixed strain rate(). The results showed that deformation twining occurred actively only in the RD specimens, which promoted homogeneous deformation as compared to the ND specimens. The effect of temperature on the formation of deformation twins was also investigated, and the slip/twin transition temperature was found to be approximately .

The influence of initial texture on the formation of primary twin system of AZ31 Magnesium rolled plate was investigated in this work. Uniaxial compression tests were carried out on samples cut along the rolling direction (RD) and normal direction (ND) of rolled AZ31 Mg plate at various temperatures (RT, 150, 200, 250, 300, 350, 400, 450°C) with the fixed strain rate (0.01s-1). The results showed that the primary twinning system of AZ31 Mg alloy (c-axis extension twin) occurred actively in the RD compression specimens, which promoted homogeneous deformation as compared to the ND compression specimens. The effect of temperature on the formation of deformation twins was also investigated, and slip/twin transition temperature was found to be 250°C.

Large scale of loess has been applied on the south - sea shore of the Korean peninsula to treat red tides, due to many fishery's devastation by red tides every year. However, coastal ecosystem is ruined by the huge amount of loess applied every year. Almost all creatures, living under water such as sea weeds, clams, and fishes, where loess was applied, are disappearing. In this paper, alternative methods of the loess application are investigated. The amount of loess could be reduced by the alternative methods, Especially, loess mixed with calcium oxide has excellent effects to reduce Cochlodinium polykrikoides numbers. It was found that when loess is used with calcium oxide(CaO), removal efficiency of red tides is highly increased. Moreover, the amount of loess could be reduced dramatically.

In advanced lithography, controlling the overlay budget is one of the most critical requirements. For device nodes at 10nm and below, there are many process-based sources of surface displacement that contribute to the lithography overlay budget that are independent of the lithography process, i.e. etch, anneal, CMP, etc. By developing an understanding of how process-induced surface displacement impacts overlay, displacement information can be fed-forward to the lithography tool for overlay correction during the lithography process. This paper describes the use of displacement measurement technology, the Coherent Gradient Sensing (CGS) interferometer, to characterize the effects of process-induced overlay error on the overlay budget through several processes in a typical semiconductor process flow. The CGS technique facilitates the generation of high-density displacement maps (>3 million points on 300mm wafer) such that the stresses induced die-by-die and process-by-process can be tracked in detail. Case studies are presented that summarize the use of the CGS data to reveal correlations between displacement variation and overlay variation, and demonstrate how feed forward can be applied for controlling overlay error.

In this study, optimum processing conditions for strip-cast AZ31 Mg alloy was investigated on the basis of processing map and microstructural analysis. To obtain the processing map, isothermal compression tests were carried out to a strain of 0.5 at temperatures of 200 ∼ 400°C with the strain rates of 0.01 ∼ 10s-1. It was found that maximum efficiency indicating the optimum processing condition occurred at 300°C and 10s-1. The possible deformation mechanisms operating at high temperature was also discussed.

Characteristics of high burnup UO2 fuel such as threshold burnup for the formation of high burnup microstructure (rim), rim average burnup and rim width were estimated and then the thermal conductivity degradation due to the porous rim region was investigated. The threshold burnup for rim formation was estimated as a function of temperature and fission rate using Rest's model. The calculated threshold burnup, which shows a particular dependence on temperature, ranges from 40 to 50MWd/kgU at typical fuel periphery temperatures of 400 to 600°C. In addition, the rim average burnup and the rim width were obtained by statistical analysis of the data available in open literature. To consider the additional degradation of thermal conductivity in the rim region, a formula for rim porosity was presented with the assumption that rim pores are overpressurized and that all the produced fission gases are retained in the rim pores. To estimate the thermal conductivity in the porous rim using the general correction meth...