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Durability Characteristics in Concrete with Ternary Blended Concrete and Low Fineness GGBFS (삼성분계 콘크리트와 저분말도 슬래그를 혼입한 콘크리트의 내구 특성)

  • Kim, Tae-Hoon;Jang, Seung-Yup;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.287-294
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    • 2019
  • GGBFS(Ground Granulated Blast Furnace Slag) has been widely used in concrete for its excellent resistance chloride and chemical attack, however cracks due to hydration heat and dry shrinkage are reported. In many International Standards, GGBFS with low fineness of 3,000 grade is classified for wide commercialization and crack control. In this paper, the mechanical and durability performance of concrete were investigated through two mix proportions; One (BS) has 50% of w/b(water to binder) ratio and 60% replacement ratio with low-fineness GGBFS, and the other (TS) has 50% of w/b and 60% replacement ratio with 4000 grade and FA (Fly Ash). The strength difference between TS and BS concrete was not great from 3 day to 91 day of age, and BS showed excellent performance for chloride diffusion and carbonation resistance. Two mixtures also indicate a high durability index (more than 90.0) for freezing-thawing since they contain sufficient air content. Through improvement of strength in low fineness GGBFS concrete at early age, mass concrete with low hydration heat and high durability can be manufactured.

Sulfate Resistance of Alkali-Activated Materials Mortar (알칼리 활성화 결합재 활용 모르타르의 황산염 침식 저항성)

  • Park, Kwang-Min;Cho, Young-Keun;Lee, Bong-Chun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.94-101
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    • 2016
  • This paper presents an investigation into the durability alkali-activated materials(AAM) mortar and paste samples manufactured using fly-ash(FA) and ground granulated blast furnace slag(GGBFS) exposed to a sulfate environment with different GGBFS replace ratios(0, 30, 50 and 100%), sodium silicate modules($Ms[SiO_2/Na_2O]$ 1.0, 1.5 and 2.0) and initial curing temperatures($23^{\circ}C$ and $70^{\circ}C$). The tests involved immersions for a period of 6 months into 10% solutions of sodium sulfate and magnesium sulfate. The evolution of compressive strength, weight, length expansion and microstructural observation such as x-ray diffraction were studied. As a results, as higher GGBFS replace ratio or Ms shown higher compressive strengths on 28 days. In case of immersed in 10% sodium sulfate solution, the samples shows increase in long-term strength. However, for samples immersed in magnesium sulfate solutions, the general observation was that the compressive strength decreased after immersion. The most drastic reduction of compressive strength and expansion of weight and length occurred when GGBFS or Ms ratios were higher. Also, the XRD analysis of samples immersed in magnesium sulfate indicated that expansion of AAM caused by gypsum($CaSO_4{\cdot}2H_2O$); the gypsum increased up to 6 months continuously.

VENGEANCE, VIOLENCE, VAMPIRES: Dark Humour in the Films of Park Chan-wook

  • Hughes, Jessica
    • Cross-Cultural Studies
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    • v.28
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    • pp.17-36
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    • 2012
  • This essay places the South Korean film Thirst (2009) within Park Chan-wook's oeuvre as a filmmaker notorious for graphic depictions of violence and revenge. Park's use of dark humour in his films, which is emphasized in Thirst perhaps more than ever, allows for a more self-aware depiction of violence, where both the viewer and the protagonist are awakened to the futility of revenge. This ultimately paints his characters as fascinatingly crazy - simultaneously heroes, villains, and victims. Film theorist Wes D. Gehring's three themes of dark humour ('man as beast,' 'the absurdity of the world,' and 'the omnipresence of death') become most obvious in Park's most recent film, which pays closer attention to character development through narrative detail. Rather than portraying the characters as sentimental, dark humour depicts their misfortunes in an alternative way, allowing for consideration of such taboo subjects as religion, adultery, and death/suicide. These issues are further tackled through Thirst's portrayal of its vampire protagonist, which ultimately de-mystifies the traditional vampire figure. While this character has more often been associated with romance, exoticism and the mystical powers of the supernatural, Thirst takes relatively little from the demons of Nosferatu (Murnau, 1922) and various other Dracula adaptations, nor the romantic figures of Interview with the Vampire (Jordan, 1994), and Twilight (Hardwicke, 2008). Instead, it is part of a much smaller group of contemporary vampire films, which are rather informed by a postmodern reconfiguration of the monster. Thus, this paper examines Thirst as an important contribution to the global and hybrid nature of those films in which postmodern vampires are sympathetic and de-mystified, exhibiting symptoms stemming from a natural illness or misfortune. Park's undertaking of a vampire film allows for a complex balance between narrative and visuals through his focus on the Western implications of this myth within Korean cinema. This combination of international references and traditional Korean culture marks it as highly conscious of New Korean Cinema's focus on globalization. With Thirst, Park successfully unites familiar images of the vampire hunting and feeding, with more stylistically distinct, grotesque images of violence and revenge. In this sense, dark humour highlights the less charming aspects of the vampire struggling to survive, most effective in scenes depicting the protagonist feeding from his friend's IV in the hospital, and sitting in the sunlight, slowly turning to ash, in the final minutes of the film. The international appeal of Park's style, combining conventions of the horror/thriller genre with his own mixture of dark humour and non-linear narrative, is epitomized in Thirst, which underscores South Korea's growing global interest with its overt international framework. Furthermore, he portrayal of the vampire as a sympathetic figure allows for a shift away from the conventional focus on myth and the exotic, toward a renewed construction of the vampire in terms of its contribution to generic hybridization and cultural adaptation.

Development of Environmentally Friendly Backfill Materials for Underground Power Cables Considering Thermal Resistivity (열 저항특성을 고려한 지중송전관로 친환경 되메움재 개발)

  • Kim, Daehong;Oh, Gidae
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.1
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    • pp.13-26
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    • 2011
  • Because the allowable current loading of buried electrical transmission cables is frequently limited by the maximum permissible temperature of the cable or of the surrounding ground, there is a need for cable backfill materials to be maintained at a low thermal resistivity during the service period. Temperatures greater than $50^{\circ}C$ to $60^{\circ}C$ may lead to breakdown of cable insulation and thermal runaway if the surrounding backfill material is unable to dissipate the heat as rapidly as it is generated. This paper describes the results of studies aimed at the development of backfill material to reduce the thermal resistivity. A large number of different additive materials were tested to determine their applicability as a substitute material. The results of Dong-rim river sand (relatively uniform) show that as water content level increases, thermal resistivity tends to decrease, whereas the thermal resistivity on dry condition is very high value($260^{\circ}C-cm/watt$). In addition, other materials(such as Jinsan granite screenings, A-2(sand and gravel mixture), E-1(rubble and granite screenings mixture) and SGFC(sand, gravel, fly-ash and cement mixture)) are well-graded materials with low thermal resistivity($100^{\circ}C-cm/watt$ when dry). Based on this research, 4 types of improved materials were suggested as the environmentally friendly backfill materials with low thermal resistivity.

Study on Optimum Mixture Design for Service Life of RC Structure subjected to Chloride Attack - Genetic Algorithm Application (염해에 노출된 콘크리트의 내구수명 확보를 위한 최적 배합 도출에 대한 연구 - 유전자 알고리즘의 적용)

  • Kwon, Seung-Jun;Lee, Sung Chil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.5A
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    • pp.433-442
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    • 2010
  • A control of chloride diffusion coefficient is very essential for service life of reinforced concrete (RC) structures exposed to chloride attack so that much studies have been focused on this work. The purpose of this study is to derive the intended diffusion coefficient which satisfies intended service life and propose a technique for optimum concrete mixture through genetic algorithm(GA). For this study, 30 data with mixture proportions and related diffusion coefficients are analyzed. Utilizing 27 data, fitness function for diffusion coefficient is obtained with variables of water to binder ratio(W/B), weight of cement, mineral admixture(slag, flay ash, and silica fume), sand, and coarse aggregate. 3 data are used for verification of the results from GA. Average error from fitness function is observed to 18.7% for 27 data for diffusion coefficient with 16.0% of coefficient of variance. For the verification using 3 data, a range of error for mixture proportions through GA is evaluated to 0.3~9.3% in 3 given diffusion coefficients. Assuming the durability design parameters like intended service life, cover depth, surface chloride content, and replacement ratio of mineral admixture, target diffusion coefficient, where exterior conditions like relative humidity(R.H.) and temperature, is derived and optimum design mixtures for concrete are proposed. In this paper, applicability of GA is attempted for durability mixture design and the proposed technique would be improved with enhancement of comprehensive data set including wider range of diffusion coefficients.

Co-incineration Characteristics of Sewage Sludge and Industrial Waste Using the Rotary Kiln Incinerator (로타리킬른 소각로를 이용한 하수슬러지와 사업장폐기물의 혼합소각 특성)

  • Yang, Dong-Jib;Ko, Jae-Cheol;Kim, Jeong-Keun;Park, Hui-Jae;Park, Joon-Seok
    • Journal of the Korea Organic Resources Recycling Association
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    • v.17 no.3
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    • pp.91-99
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    • 2009
  • This research were performed to evaluate co-incineration characteristics of sewage sludge and industrial waste in rotary kiln incinerator, and provide the fundamental data. Plastic portion (42.55%) in this industrial waste showed over 3 times higher than that (11.92%) of paper. Korean proximate analysis of the waste mixed with sewage sludge and industrial waste (3 : 7, volumetric basis) showed 16.3% of moisture, 70.5% of volatile solids, and 13.2% of ash, respectively. Low heating value of the mixed waste was 4,513kcal/kg. So it was thought that the mixed waste of sewage sludge and industrial waste (containing 43% of plastics and 12% papers) has enough heating value for co-incineration. The incineration of mixed waste showed the lowest SOx and NOx concentrations at $700^{\circ}C$. However, the operation at $950^{\circ}C$ was feasible in considering dioxin and the other hazardous gases. It was concluded that use of $Ca(OH)_2$ should be under investigation for the operation at $950^{\circ}C$.

Effect of Sawdust Moisture Content and Particle Size on The Fuel Characteristics of Wood Pellet Fabricated with Quercus mongolica, Pinus densiflora and Larix kaempferi Sawdust (신갈나무, 소나무, 낙엽송 목분의 함수율 및 크기가 목재펠릿의 연료적 특성에 미치는 영향)

  • Kim, Seong-ho;Yang, In;Han, Gyu-Seong
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.6
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    • pp.757-767
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    • 2015
  • This study was conducted to investigate the effects of moisture content and particle size of sawdust on the fuel characteristics of wood pellets produced with Mongolian oak (Quercus mongolica, QUM), red pine (Pinus densiflora, PID) and larch (Larix kaempferi, LAK) sawdust using a flat-die pelletizer. Prior to produce wood pellets, the sawdust was controlled to the moisture content of 8, 11, 12% and was screened to the particle size of 2 and 4 mesh. In the analysis of its chemical composition, QUM had a high ash content, and PID and LAK contained large amount of lignin. In case of the fuel characteristics, PID pellets had the lowest moisture content of pellets (P-MC), and LAR pellets was found to have the highest bilk density (BD) and durability (DU). With the increase of moisture content of sawdust (S-MC), P-MC and DU of QUM, PID and LAK pellets increased, but BD of QUM and LAK pellets decreased. When size of sawdust used for the production of wood pellets decreased, P-MC and BD of LAK pellets and BD of QUM pellets increased. Decrease of particle size contributed to the increase of DU of QUM, PID and LAK pellets. In addition, BD and DU of QUM pellets produced with 12% S-MC sawdust increased as its particle size reduced. For LAK pellets, DU was not influence by particle size in the S-MCs of 10% and 12%, but increased with the decrease of particle size in the S-MC of 8%. Based on the results and economical aspects, 10% MC and 2 mesh paricle size for QUM sawdust and 12% MC and 2 mesh particle size for PID sawdust might be optimal conditions for pellets production, and fuel characteristics of wood pellets produced by the conditions greatly exceeded the minimum requirements for the $1^{st}$-grade wood pellets of the standard designated by Korea Forest Research Institute.

Separation of Reducing Sugars from Rape Stalk by Acid Hydrolysis and Fabrication of Fuel Pellets from its Residues (산가수분해한 유채대로부터 유리당의 분리 및 이의 잔사로부터 펠릿의 제조)

  • Yang, In;Ahn, Byoung Jun;Kim, Myeong-Yong;Oh, Sei Chang;Ahn, Sye Hee;Choi, In-Gyu;Kim, Yong-Hyun;Han, Gyu-Seong
    • Korean Journal of Plant Resources
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    • v.27 no.1
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    • pp.60-71
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    • 2014
  • This study was conducted to identify the potential of rape stalk as a raw material for biorefinery process of rape flower. At first, rape stalk (RS) was immersed in distilled water (DW), acetic acid (AA), oxalic acid (OA), sulfuric acid (SA) and sodium hydroxide (SH) solutions, and the content of reducing sugars liberated from immersed RS was analyzed. Glucose, xylose, arabinose and sucrose were detected varying with the immersion type. In particular, 1% AA-immersion of RS for 72 hr was the most effective conditions to liberate glucose from RS. Secondly, the RS residues were used for elementary analysis and fabrication of fuel pellets. In addition to the solution type, concentration of immersion solutions (0%, 1%, 2%) and immersion time (24, 72, 120 hr) were used as experimental factors. The contents of nitrogen, sulfur and chlorine reduced effectively through the immersion of RS in DW, AA and OA solutions. For properties of RS-based pellets, bulk density and higher heating value of RS-based pellets greatly increased with the immersion of RS, and the qualities were much higher than those of the A-grade pellet of the EN standards. Ash content decreased remarkably through the immersion of RS, and was satisfied with the A-grade pellet standard. Durability was negatively affected by the immersion of RS, and did not reached to B-grade of the EN standard. In conclusion, acid immersion of RS can be a pretreatment method for the production of fuel pellet and bioethanol, but use of the immersed RS for the production of high-quality pellets might be restricted due to low durability of immersed-RS pellets. Therefore, further studies, such as investigation of detailed immersion conditions, fabrication of mixed pellets with wooden materials and addition of binders, are needed to resolve the problems.

Pyrolysis Characteristics of CCL(Copper Clad Laminate) Based Paper/Phenolic Resin Composites (종이/페놀수지가 주성분인 동박적층판(Copper Clad Laminate)의 열분해 특성)

  • Song, Jae-Hun;Kim, Seung-Do;Ahn, Hyun-Cheol;Kim, Gyung-Soo;Kim, Sang-Bum;Jung, Jae-Sung;Gong, Sung-Ho;Cho, Young-Gae
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.9
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    • pp.1013-1019
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    • 2007
  • Electronic wastes have increased tremendously. However, any reliable treatment methodologies have rarely been established. Electronic wastes have posed serious disposal problem due to their physico-chemical stability. This paper investigated the application possibility of pyrolysis for the purpose of recycling the p-CCL(phenol based Copper Clad Laminate). Thermogravimetric analysis(TGA) was used to investigate the thermal decomposition pattern of p-CCL. We elucidated the characteristics of pyrolysis by-products at operating temperatures of 280, 350 and $600^{\circ}C$. GC/MS and FT-IR were used to characterize the liquid by-products along with general characterization methods such as Ultimate Analysis, Proximate Analysis and Heating Value, whereas general characterization methods were only introduced for the solid by-products. At a heating rate of $5^{\circ}C$/min, TGA curves exhibited three decomposition stages: (1) low-temperature decomposition region$(<280^{\circ}C)$, (2) medium temperature region$(280\sim350^{\circ}C)$ and (3) high-temperature region$(>350^{\circ}C)$. The major compounds of liquid by-products at low- and medium-temperatures were accounted for by water and phenol, whereas branched phenols and furans were major compounds at high-temperatures. As the temperature increases, volatile quantities decreased but the fixed carbon increased. High heating values of solid by-products($7,400\sim7,600$ kcal/kg) would suggest that the solid by-products could be applicable as fuel. In addition, high fixed carbon but low ash content of the solid by-products offered an implication that they are capable of being upgradable for adsorbent after applying appropriate activating process.

A Study on Chloride Threshold Level of Blended Cement Mortar Using Polarization Resistance Method (분극저항 측정기법을 이용한 혼합 시멘트 모르타르의 임계 염화물 농도에 대한 연구)

  • Song, Ha-Won;Lee, Chang-Hong;Lee, Kewn-Chu;Ann, Ki-Yong
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.245-253
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    • 2009
  • The importance of chloride ions in the corrosion of steel in concrete has led to the concept for chloride threshold level (CTL). The CTL can be defined as the content of chlorides at the steel depth that is necessary to sustain local passive film breakdown and hence initiate the corrosion process. Despite the importance of the CTL, due to the uncertainty determining the actual limits in various environments for chloride-induced corrosion, conservative values such as 0.4% by weight of cement or 1.2 kg in 1 $m^3$ concrete have been used in predicting the corrosion-free service life of reinforced concrete structures. The paper studies the CTL for blended cement concrete by comparing the resistance of cementitious binder to the onset of chloride-induced corrosion of steel. Mortar specimens were cast with centrally located steel rebar of 10 mm in diameter using cementitious mortars with ordinary Portland cement (OPC) and mixed mortars replaced with 30% pulverized fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF), respectively, at 0.4 of a free W/B ratio. Chlorides were admixed in mixing water ranging 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder(Based on $C1^-$). Specimens were curd 28 days at the room temperature, wrapped in polyethylene film to avoid leaching out of chloride and hydroxyl ions. Then the corrosion rate was measured using the polarization resistance method and the order of CTL for binder was determined. Thus, CTL of OPC, 60%GGBS, 30%PFA and 10%SF were determined by 1.6%, 0.45%, 0.8% and 2.15%, respectively.