• Title/Summary/Keyword: 실리카

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Catalyst Carriers Preparation and Investigation of Catalytic Activities for Partial Oxidation of Methane to Hydrogen over Ru Impregnated on SPK and SPM Catalysts (메탄의 부분산화반응으로부터 수소제조를 위한 촉매담체(SPK, SPM) 제조 및 Ru 담지 촉매의 활성도 조사)

  • Seo, Ho Joon;Fan, Shijian;Kim, Yong Sung;Jung, Do Sung;Kang, Ung Il;Cho, Yeong Bok;Kim, Sang Chai;Kwon, Oh-Yun;Sunwoo, Chang Shin;Yu, Eui Yeon
    • Korean Chemical Engineering Research
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    • v.46 no.3
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    • pp.581-584
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    • 2008
  • The catalyst carriers of the mesoporous layer compounds were prepared to carry out the partial oxidation of methane(POM) to hydrogen. The catalytic activities of POM to hydrogen were investigated over Ru(3)/SPK and Ru(3)/SPM catalyst in a fixed bed flow reactor under atmosphere. In addition, the catalysts and carriers were characterized by BET, TEM, TPR. The BET surface areas of the silica-pillared $H^+-kenyaite$(SPK) and the silica-pillared $H^+-magadite$(SPM) were $760m^2/g$ and $810m^2/g$, repectively, and the average pore sizes were 3.0 nm and 2.6 nm, repectively. The nitrogen adsorption isotherms were type IV with developed hysteresis. The TEM showed that the mesoporous layer compounds were formed well. The Ru(3)/SPK and the Ru(3)/SPM catalyst were obtained high hydrogen yields(90%, 87%), and were kept constant high hydrogen yields even about 60 hours at 973 K, $CH_4/O_2=2$, $1.25{\times}10^{-5}g-Cat.hr/ml$. The TPR peaks of Ru(3)/SPK and the Ru(3)/SPM catalyst showed the similar reducibilities around 453 K and 413 K. It could be suggested that SPK and SPM had the physicochemical properties as oxidation catalyst carries from these analysis data.

Studies on Engneering Properties of Coal Ash Obtained as Industrial Wastes (산업폐기물(産業廢棄物)로 발생(發生)되는 석탄회(石炭灰)의 토질력학적(土質力學的) 특성(特性)에 관한 연구(硏究))

  • Chun, Byung Sik;Koh, Yong Il;Oh, Min Yeoul;Kwon, Hyung Seok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.10 no.1
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    • pp.115-123
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    • 1990
  • The purpose of this study was to examine the uses of coal ash as a type of construction material. The methods of examination were chemical anlysis, soil laboratory test and the soil vibration test. Materials used were coal ash obtained as a by-product from 5 thermal power plants in Yongdong, Yongwol, Sochon(anthracite coal) and in Samchonpo and Honam (bituminous coal). Over 70% of the coal ash consisted of silica and alumina. The fly ash grain size showed a uniform distribution from fine-sand to silt, and that of the bottom ash showed from sand to gravel. The specific gravity and density of the coal ash were low. The long term strength increased gradually due to the self-setting property resulting from pozzolanic activity. The shear strength was higher than that of general soil. Cohesion and optimum moisture content of anthracite coal ash were higher than bituminous coal ash, whereas the maximum dry density was higher in bituminous coal ash. The coal ash dynamic Young's modulous curve range was similar to that of general soil. Of the results from the soil vibration test by car-running, the size relative acceleration level in the ash pond was higher than that of natural ground, but the damping ratio was lower than that of natural ground near the ash pond. The coal ash has more advantageous engineering properties than general soil with particles of the same size. For example, the California Bearing Ratio of the bottom ash at both Yongdong and Yongwol was 77~137%. Therefore we expect that if further study is done, coal ash can be used as a construction material when reclaiming seashore, construction embankments, road construction, making right-weight aggregate, or as a general construction material.

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Development and Validation of an Analytical Method for Fungicide Sedaxane Determination in Agricultural Products using LC-MS/MS (LC-MS/MS를 이용한 농산물 중 살균제 Sedaxane의 잔류시험법 개발 및 검증)

  • Cho, Sung Min;Do, Jung-Ah;Park, Shin-Min;Lee, Han Sol;Park, Ji-Su;Shin, Hye-Sun;Jang, Dong Eun;Choi, Young-Nae;Jung, Yong-hyun;Lee, Kangbong
    • Journal of Food Hygiene and Safety
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    • v.34 no.1
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    • pp.30-39
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    • 2019
  • An analytical method was developed for the determination of sedaxane in agricultural products using liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The samples were extracted with acetonitrile and partitioned with dichloromethane to remove the interference, and then purified by using silica SPE cartridges to clean up. The analytes were quantified and confirmed by using LC-MS/MS in positive ion mode using multiple reaction monitoring (MRM). The matrix-matched calibration curves were linear over the calibration ranges ($0.001-0.25{\mu}g/mL$) into a blank extract with $r^2$>0.99. For validation, recovery tests were carried out at three different concentration levels (LOQ, 10LOQ, and 50LOQ, n=5) with five replicates performed at each level. The recoveries were ranged between 74.5 to 100.8% with relative standard deviations (RSDs) of less than 12.1% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for sedaxane determination in agricultural commodities.

Implicit Distinction of the Race Underlying the Perception of Faces by Event-Related fMRI (Event-related 기능적 MRI 영상을 통한 얼굴인식과정에서 수반되는 무의식적인 인종구별)

  • Kim Jeong-Seok;Kim Bum-Soo;Jeun Sin-Soo;Jung So-Lyung;Choe Bo-Young
    • Investigative Magnetic Resonance Imaging
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    • v.9 no.1
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    • pp.43-49
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    • 2005
  • A few studies have shown that the function of fusiform face area is selectively involved in the perception of faces including a race difference. We investigated the neural substrates of the face-selective region called fusiform face area in the ventral occipital-temporal cortex and same-race memory superiority in the fusiform face area by the event-related fMRI. In our fMRI study, subjects (Oriental-Korean) performed the implicit distinction of the race while they consciously made familiar-judgments, regardless of whether they considered a face as Oriental-Korean or European-American. For race distinction as an implicit task, the fusiform face areas (FFA) and the right parahippocampal gyrus had a greater response to the presentation of Oriental-Korean faces than for the European-American faces, but in the conscious race distinction between Oriental-Korean and European-American faces, there was no significant difference observed in the FFA. These results suggest that different activation in the fusiform regions and right parahippocampal gyrus resulting from superiority of same-race memory could have implicitly taken place by the physiological processes of face recognition.

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The effect of Silano-pen on the shear bond strength of resin to feldspathic porcelain and zirconia (실라노 펜의 적용이 장석계 도재 및 지르코니아와 레진의 전단결합강도에 미치는 영향)

  • Shin, Myoung-Sik;Lee, Jeong-Yol;Kim, Min-Soo;Shin, Sang-Wan
    • The Journal of Korean Academy of Prosthodontics
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    • v.52 no.1
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    • pp.1-8
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    • 2014
  • Purpose: The purpose of this study is to evaluate the effect of applying Silano-pen to feldspathic porcelain and zirconia on shear bond strength with composite resin. Materials and methods: Feldspathic porcelain and zirconia specimens were produced into 30 per each 2 mm thick and 12 mm in diameter and their surface was made smooth and even and then embedded in acrylic resin. The specimens were divided into each Group F (Feldspathic porcelain) and Group Z (Zirconia), (1) Hydrofluoric acid etching and silane (F1 & Z1), (2) Silano-pen and silane (F2 & Z2), (3) Hydrofluoric acid etching and Silano-pen, silane (F3 & Z3). After surface conditioning, substrate surfaces of the specimen were examined by SEM. Composite resin cylinders (2 mm high, 3 mm in diameter)were bonded to specimen and shear bond strength between ceramic and composite resin was measured by using universal testing machine. The measured values were statistically analyzed by using two way ANOVA and Tukey's multiple comparison test (${\alpha}=.05$). Results: In the scanning electron micrograph of the treated ceramic surface, Group F2 and F3 appeared the high roughness and Group Z3 appeared the highest density of silica particle. In Feldspathic porcelain, the result of measuring shear bond strength showed that Group F3 was measured to be highest and Group F1 was measured to be lowest but there was no statistical significance among Groups. In zirconia, Group Z3 was measured to be highest and Group Z1 was measured to be lowest and there was statistical significance among Groups (P<.05). Conclusion: In zirconia, applying hydrofluoric acid etching and then Silano-pen and silane is effective for composite resin adhesion.

Flow Behavior and Mixing Characteristics of Rice Husk/Silica Sand/Rice Husk Ash (왕겨/모래/왕겨 회재의 유동 및 혼합 특성 연구)

  • Kim, Bo Hwa;Seo, Myung Won;Kook, Jin Woo;Choi, Hee Mang;Ra, Ho Won;Yoon, Sang Jun;Mun, Tae Young;Kim, Yong Ku;Lee, Jae Goo;Rhee, Young Woo
    • Korean Chemical Engineering Research
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    • v.54 no.4
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    • pp.533-542
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    • 2016
  • We investigate fluidization characteristics of the mixture of rice husk, silica sand and rice husk ash as a preliminary study for valuable utilization of rice husk ash obtained from gasification of rice husk in a fluidized bed reactor. As experiment valuables, the blending ratio of rice husk and sand (rice husk: sand) is selected as 5:95, 10:90, 20:80 and 30:70 on a volume base. Rice husk ash was added with 6 vol% of rice husk for each experiment and air velocity to the reactor was 0~0.63 m/s. In both rice husk/sand and rice husk/sand/ash mixture, the minimum fluidization velocity (Umf) is observed as 0.19~0.21 m/s at feeding of 0~10 vol.% of rice husk and 0.30 m/s at feeding of 20 vol.% of rice husk. With increasing the amount of rice husk up to 30 vol.%, $U_{mf}$ can not measure due to segregation behavior. The mixing index for each experiment is determined using mixing index equation proposed by Brereton and Grace. The mixing index of the mixture of rice husk/sand and rice husk/sand/ash was 0.8~1 and 0.88~1, respectively. The optimum fluidization condition was found for the good mixing and separation of rice husk ash.

Phase Equilibria of the System Pd-Sb-Te and Its Geological Implications (팔라듐-안티몬-테루르 계(系)의 상평형(相平衡)과 지질학적(地質學的) 의의(意義))

  • Kim, Won-Sa;Chao, George Y.
    • Economic and Environmental Geology
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    • v.26 no.3
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    • pp.327-335
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    • 1993
  • Phase relations in the system Pd-Sb-Te were investigated at $1000^{\circ}$, $800^{\circ}$, and $600^{\circ}C$, using the sealed-capsule technique; the quenched products were studied by reflected light microscopy, X-ray diffraction, and electron microprobe analysis. At $1000^{\circ}C$, the solid phases Pd, $Pd_{20}Sb_7$, $Pd_8Sb_3$, $Pd_{31}Sb_{12}$, and $Pd_5Sb_2$ are stable with a liquid phase that occupies most of the isothermal diagram. Additional solid phases at $800^{\circ}C$ are $Pd_5Sb_3$, PdSb, $Pd_8Te_3$, $Pd_7Te_3$, and a continuous $Pd_{20}Te_7-Pd_{20}Sb_7$ solid solution becomes stable. At $600^{\circ}$, $PdSb_2$, $Pd_{17}Te_4$, $Pd_9Te_4$, PdTe, $PdTe_2$, $Sb_2Te_3$, and Sb and continuous PdSb-PdTe and $PdTe-PdTe_2$ solid solutions are stable. All the solid phases exhibit solid solution, mainly by substitution between Sb and Te to an extent that varies with temperature of formation. The maximum substitution (at.%) of Te for Sb in the Pd-Sb phases is: 44.3 in $Pd_8Sb_3$, 52.0 in $Pd_{31}Sb_{12}$, 46.2 in $Pd_5Sb_2$ at $800^{\circ}C$; 15.3 in $Pd_5Sb_3$, 68.3 in $PdSb_2$ at $600^{\circ}C$. The maximum substitution (at.%) of Sb for Te in the Pd-Te phases is 34.5 in $Pd_5Sb_3$ at $800^{\circ}C$, and 41.6 in $Pd_7Te_3$, 5.2 in $Pd_{17}T_4$, 12.4 in $Pd_9Te_4$, and 19.1 in $PdTe_2$ at $600^{\circ}C$. Physical properties and X-ray data of the synthetic $Pd_9Te_4$, PdTe, $PdTe_2$, $Pd_8Sb_3$, PdSb, and $Sb_2Te_3$ correspond very well with those of telluropalladinite, kotulskite, merenskyite, mertieite II, sudburyite, and tellurantimony, respectively. Because X-ray powder diffraction data consistently reveal a 310 peak ($2.035{\AA}$), the $PdSb_2$ phase is most probably of cubic structure with space group $P2_13$. The X-ray powder pattern of a phase with PdSbTe composition, synthesized at $600^{\circ}C$, compares well with that of testibipalladite. Therefore, testibiopalladite may be a member of the $PdSb_2-Pd(Sb_{0.32}Te_{0.68})$ solid solution series which is cubic and $P2_13$ in symmetry. Thus the ideal fonnula for testibiopalladite, presently PdSbTe, must be revised to PdTe(Sb, Te). Borovskite($pd_3SbTe_4$) has not been found in the synthetic system in the temperature range $1000^{\circ}-600^{\circ}C$.

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Occurrence and Chemical Composition of Dolomite from Komdok Pb-Zn Deposit (검덕 연-아연 광상의 돌로마이트 산상과 화학조성)

  • Yoo, Bong Chul
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.2
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    • pp.107-120
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    • 2021
  • The Komdok Pb-Zn deposit, which is the largest Pb-Zn deposit in Korea, is located at the Hyesan-Riwon metallogenic zone in Jiao Liao Ji belt included Paleoproterozoic Macheolryeong group. The geology of this deposit consists of Paleoproterozoic metasedimentary rocks, Jurassic Mantapsan intrusive rocks and Cenozoic basalt. The Komdok deposit which is a SEDEX type deposit occurs as layer ore and vein ore in the Paleoproterozoic metasedimentary rocks. Based on mineral petrography and paragenesis, dolomites from this deposit are classified four types (1. dolomite (D0) as hostrock, 2. early dolomite (D1) associated with tremolite, actinolite, diopside, sphalerite and galena from amphibolite facies, 3. late dolomite (D2) associated with talc, calcite, quartz, sphalerite and galena from amphibolite facies, 4. dolomite (D3) associated with white mica, chlorite, sphalerite and galena from quartz vein). The structural formulars of dolomites are determined to be Ca1.00-1.20Mg0.80-0.99Fe0.00-0.01Zn0.00-0.02(CO3)2(D0), Ca1.00-1.02M0.97-0.99Fe0.00-0.01Zn0.00-0.02(CO3)2(D1), Ca0.99-1.03Mg0.93-0.98Fe0.01-0.05Mn0.00-0.01As0.00-0.01(CO3)2(D2) and Ca0.95-1.04Mg0.59-0.68Fe0.30-0.36Mn0.00-0.01 (CO3)2(D3), respectively. It means that dolomites from Komdok deposit have higher content of trace elements (FeO, MnO, HfO2, ZnO, PbO, Sb2O5 and As2O5) compared to the theoretical composition of dolomite. These trace elements (FeO, MnO, ZnO, Sb2O5 and As2O5) show increase and decrease trend according to paragenetic sequence, but HfO2 and PbO elements no show increase and decrease trend according to paragenetic sequence. Dolomites correspond to Ferroan dolomite (D0, D1 and D2), and Ferroan dolomite and ankerite (D3), respectively. Therefore, 1) dolomite (D0) as hostrock was formed by subsequent diagenesis after sedimentation of Paleoproterozoic (2012~1700 Ma) silica-bearing dolomite in the marine evaporative environment. 2) Early dolomite (D1) was formed by hydrothermal metasomatism origined metamorphism (amphibolite facies) associated with intrusion (1890~1680 Ma) of Paleoproterozoic Riwon complex. 3) Late dolomte (D2) was formed from residual fluid by a decrease of temperature and pressure. and dolomite (D3) in quartz vein was formed by intrusion (213~181 Ma) of Jurassic Mantapsan intrusive rocks.

A study for Shear Strength Characteristics of Frozen Soils under Various Temperature Conditions and Vertical Confining Pressures (동결온도조건 및 수직구속응력에 따른 동결토의 전단강도 변화에 관한 연구)

  • Lee, Joonyong;Choi, Changho
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.11
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    • pp.51-60
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    • 2012
  • In order to characterize the shear strength of the frozen sand for foundation design in cold region and prediction of adfreeze bond strength, many researchers developed test techniques and carried out many tests to analyze shear strength properties of the frozen sand for half a century. However, many studies for shear strength properties of the frozen sand have been carried out with limited circumstances, even though shear strength of the froze sand can be affected by various influence factors such as soil type, temperature conditions, and magnitude of normal stress. In this study, direct shear test equipment was used to analyze the shear strength characteristics of the frozen sand. Direct shear test equipment was designed for cold weather, and the direct shear tests were carried out inside of large-scaled low temperature chamber. Three soil types-two uniform sands and one well graded soil were used to analyze the shear strength of the frozen sand with three different temperature conditions and three different vertical confining pressures. In this research, a series of direct shear tests for shear strength of the frozen sand have been conducted to demonstrate the efficiency of effectiveness of the test equipment and low temperature chamber. This research also showed that shear strength of the froze sand increased with decreasing temperature condition, but the influence of vertical confining pressure was insignificant to the shear strength of the frozen sand.

Adsorption Characteristics of the Heavy Metals, Cd(II) and Pb(II) Ions, on the Si-Immobilized Ulva pertusa (실리카고정 구멍갈파래에 대한 중금속 Cd(II), Pb(II)이온의 흡착 특성)

  • Park, Kwang-Ha;Park, Mi-A;Kim, Young-Ha;Choi, Bong-Jong
    • Analytical Science and Technology
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    • v.12 no.2
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    • pp.116-124
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    • 1999
  • Adsorption characteristics of heavy metal ions, Cd(II) and Pb(II), on eastcoast-living algae, ulva pertusa, has been studied in our experiment. The Maximum adsorption amount of Cd(II) and Pb(II) ions on 1 g of the ulva pertusa were 2.3 mg, 3.1 mg in alkaline and 2.0 mg, 2.8 mg in acidic solution. However 3.4 mg, 7.3 mg in alkaline and 3.1 mg, 6.5 mg in acidic solution were shown on the Si-immobilized ulva pertusa in the same condition. Thus, Si-immobilized ulva pertusa adsorbs more amount of heavy metals, Cd(II), Pb(II), than the ulva pertusa, and more effective absorbent in alkaline. Furthermore, more amounts of Pb(II) ion were absorbed compare to Cd(II) ion in our work. Recovery ratio of Cd(II) and Pb(II) ions on the ulva pertusa were 55.0~61.0%, 59.7~66.8% respectively and 87.6~97.5%, 83.5~99.3% on the Si-immobilized ulva pertusa.

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