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CO and C3H8 Oxidations over Supported Co3O4, Pt and Co3O4-Pt Catalysts: Effect on Their Preparation Methods and Supports, and Catalyst Deactivation (Co3O4, Pt 및 Co3O4-Pt 담지 촉매상에서 CO/C3H8 산화반응: 담체 및 제조법에 따른 영향과 촉매 비활성화)

  • Kim, Moon-Hyeon;Kim, Dong-Woo;Ham, Sung-Won
    • Journal of Environmental Science International
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    • v.20 no.2
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    • pp.251-260
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    • 2011
  • $TiO_2$- and $SiO_2$-supported $Co_3O_4$, Pt and $Co_3O_4$-Pt catalysts have been studied for CO and $C_3H_8$ oxidations at temperatures less than $250^{\circ}C$ which is a lower limit of light-off temperatures to oxidize them during emission test cycles of gasoline-fueled automotives with TWCs (three-way catalytic converters) consisting mainly of Pt, Pd and Rh. All the catalysts after appropriate activation such as calcination at $350^{\circ}C$ and reduction at $400^{\circ}C$ exhibited significant dependence on both their preparation techniques and supports upon CO oxidation at chosen temperatures. A Pt/$TiO_2$ catalyst prepared by using an ion-exchange method (IE) has much better activity for such CO oxidation because of smaller Pt nanoparticles, compared to a supported Pt obtained via an incipient wetness (IW). Supported $Co_3O_4$-only catalysts are very active for CO oxidation even at $100^{\circ}C$, but the use of $TiO_2$ as a support and the IW technique give the best performances. These effects on supports and preparation methods were indicated for $Co_3O_4$-Pt catalysts. Based on activity profiles of CO oxidation at $100^{\circ}C$ over a physical mixture of supported Pt and $Co_3O_4$ after activation under different conditions, and typical light-off temperatures of CO and unburned hydrocarbons in common TWCs as tested for $C_3H_8$ oxidation at $250^{\circ}C$ with a Pt-exchanged $SiO_2$ catalyst, this study may offer an useful approach to substitute $Co_3O_4$ for a part of platinum group metals, particularly Pt, thereby lowering the usage of the precious metals.

Seasonal Change in the CO2 Fixation Rate and Water-Use Efficiency of Broad-leaved Tree Species on Jeju Island (제주지역 주요 활엽수의 대기 중 CO2 흡수율과 수분이용효율의 계절적 변화)

  • Oh, Soonja;Kim, Hyoun-Chol;Kang, Hee-Suk;Shin, Chang-Hoon;Koh, Seok Chan
    • Journal of Environmental Science International
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    • v.29 no.2
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    • pp.123-132
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    • 2020
  • Seasonal changes in the CO2 fixation rate and water-use efficiency in the leaves of six evergreen and two deciduous broad-leaved tree species on Jeju Island, Korea, were measured using a portable photosynthesis analyzer, to identify which species are most efficient in taking up CO2 from the air. The CO2 fixation rate was high in the deciduous species in spring and summer and decreased in fall, whereas it was high in the evergreen species in summer and fall and decreased in winter. The rate remained high in the deciduous tree Prunus yedoensis from spring to fall (> 7.1 μmol CO2/m2/s) and in two evergreen trees, Castanopsis cuspidata var. sieboldii and Cinnamomum camphora, in summer and fall (7.0 9.9 μmol CO2/㎡/s). Therefore, these tree species fix atmospheric CO2 effectively. The water-use efficiency was higher in evergreen species than in deciduous species regardless of the season. Exceptionally, it was high in the deciduous species Zelkova serrata in spring and summer (> 100 μmol CO2/mol H2O), suggesting that Z. serrata is a useful tree for dry conditions due to its tolerance of water stress. The regressions of the CO2 fixation rate versus the evaporation rate and stomatal conductance were linear and non-linear, respectively. This suggests that the stomatal activity of leaves plays an important part in CO2 fixation of plants. In conclusion, C. cuspidata var. sieboldii, C. camphora, and P. yedoensis should be planted along roads or in urban spaces for the greening of cities and mitigation of CO2 concentrations in the air.

A Study on the Adoption of Cyclotron Decommissioning Plan Criteria by the Analysis of Domestic Relocation and Abroad Dismantling Practices (국내 사이클로트론 이전 및 해외 해체 사례 분석을 통한 해체 계획 기준 도입 연구)

  • Woo, Rina;Kim, Yongmin;Song, Minchul;Cho, Daehyung;Lee, Jaesung;Kim, Wantae
    • Journal of Radiation Protection and Research
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    • v.38 no.2
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    • pp.91-99
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    • 2013
  • There are many reasons for decommissioning of cyclotron such as not only age-related deficiency, any serious wear or damage but also relocation, upgrade and changing mission. Decommission of cyclotron in USA and EU give rise to a lot of low-level radioactive waste and costs. Various research on decommissioning of particle accelerator have been carried to reduce the cost of decommissioning in USA and EU. In USA, the NRC require DFP (Decommissioning Funding Plan) to authorized licenser by 10 CFR Part 30.35. To resolve radioactive waste problem and reduce the estimated cost of cyclotron decommissioning, we should consider technical aspects (decommissioning procedures, decontamination techniques, etc.) and safety aspects(residual radioactivity, the expected dose, etc) for decommissioning. In this study, we analyzed practical information on the decommissioning of cyclotron in ANL (Argonne National Laboratory) and Belgium (EU). And we investigated the experience on the cyclotron relocation from SNUH (Seoul National University Hospital) to SKKU (Sungkyunkwan University). From these results, we provide the basic data for establishing of relevant standards on domestic cyclotron decommissioning. It is necessary to adopt the DFP for safe and economic decommissioning and waste recycling. These result could be utilized for the establishment on the standards and useful requirements.

Seasonal Occurrence and Age Structure of Paromius exiguus (Distant) (Heteroptera: Lygaeidae) on Major Host Plants (흑다리긴노린재[Paromius exiguus (Distant)](Heteroptera: Lygaeidae)의 발생소장과 주요 기주에서 시기별 연령분포)

  • Park, Chang-Gyu;Park, Hong-Hyun;Uhm, Ki-Baik;Lee, Joon-Ho
    • Korean journal of applied entomology
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    • v.48 no.1
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    • pp.21-27
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    • 2009
  • Paromius exiguus (Distant) has caused serious damage by pecky grains around Gimpo paddy fields in 2001. We conducted field and laboratory studies to determine the seasonal occurrence and age distribution of P. exiguus on the three major host plants. The overwintering P. exiguus was found mainly on the basal part of gramineae weeds in various localities. After overwintering, in mid-May, the adults aggregated on the grain parts of Imperata cylindrica, laid their eggs and nymphs developed into adults on the same host plants. By the time, the Calamagrostis epigeios colony had newly occupied I. cylindrica areas, the nymphs and adults of first generation had already moved to the second host. The second generation of P. exiguus, after having completed its life cycle on C. epigeios, the newly emerged adults migrated to the rice plants and other gramineae weeds in early August. Afterwards, they complete its third generation cycle where they can move to the overwintering site again. P. exiguus has the five nymphal stages and each nymphal stage could be determined by head or prothoracic width. On the I. cylindrica and O. sativa hosts, the age distribution of P. exiguus showed a simple structure as each stage ratio increased stepwise with time. But in case of C. epigeios, as the newly emerged adults and immature nymphs continuously migrate after a month from the I. cylindrica, the age structure became remarkably complex. The peak nymphal density was observed when the ratio of third and forth instar was the highest in the population. The finding about the specific age structure on each generation of the insect would be very useful in control decision making on the major host plants. It is also important to consider the host's specificity to pesticide sensitivity in relation to various nymphal stages.

Comparative evaluation of computed tomography for dental implants on the mandibular edentulous area (하악 무치악 부위의 임플란트 이식을 위한 전산화단층촬영 영상의 비교 평가)

  • Sun, Kyung-Hoon;Jeong, Ho-Gul;Park, Hyok;Park, Chang-Seo;Kim, Kee-Deog
    • Imaging Science in Dentistry
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    • v.39 no.1
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    • pp.27-33
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    • 2009
  • Purpose: The purpose of this study was to evaluate the clinical usefulness of the recently developed multi-detector computed tomography and cone beam computed tomography in pre-operative implant evaluation, by comparing them with the single detector computed tomography, already confirmed for accuracy in this area. Materials and Methods: Five partially edentulous dry human mandibles, with $1{\times}1mm$ gutta percha cones, placed in 5mm intervals posterior to the mental foramen on each side of the buccal part of the mandible, were used in this study. They were scanned as follows: 1) Single detector computed tomography: slice thickness 1mm, 200mA, 120kV 2) Multi-detector computed tomography: slice thickness 0.75mm, 250mA, 120kV 3) Cone beam computed tomography: 15mAs, 120kV Axial images acquired from three computed tomographies were transferred to personal computer, and then reformatted cross-sectional images were generated using V-Implant $2.0^{(R)}$ (CyberMed Inc., Seoul, Korea) software. Among the cross-sectional images of the gutta perch a cone, placed in the buccal body of the mandible, the most precise cross section was selected as the measuring point and the distance from the most superior border of the mandibular canal to the alveolar crest was measured and analyzed 10 times by a dentist. Results: There were no significant intraobserver differences in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). There were no significant differences among single detector computed tomography, multi-detector computed tomography and cone beam computed tomography in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). Conclusion: Multi-detector computed tomography and cone beam computed tomography are clinically useful in the evaluation of pre-operative site for mandibular dental implants, with consideration for radiation exposure dose and scanning time.

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Geographical interpretation of the Chapter on Economy in (財用篇) the Mangiyoram ("만기요람(萬機要覽)" "재용편(財用篇)"의 지리적 해석)

  • Sohn, Yong-Taek
    • Journal of the Economic Geographical Society of Korea
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    • v.12 no.2
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    • pp.195-214
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    • 2009
  • The Mangi yoram("萬機要覽"), a guidebook of state affairs, was published by royal command in the late Joseon period. Its chapters on financial affairs(財用篇) are particularly remarkable, as they explain on all aspects of the national finance of the late Joseon period in a clear manner. The financial part of the Mangi yoram includes metallic mineral resources, such as the location of gold, silver, copper, lead deposits and the prosperity and decline of the mines, and the various uses of each of the minerals. These are still regarded as valuable resources. Its contents on agricultural geography comprise not only the total yearly output of grains, paddyfields and dryfields, their taxation and standards of taxation, but also ginseng which was famous in the outside world in the pre-modern era. The book also clearly explains distribution of agricultural dikes for irrigation and their functions. The book also contains information on forestry geography, e.g. the varieties of pine trees and their distribution and mountain containment policies. Contents related to commercial geography consist of material on different types of markets such as the yukuijeon(六矣廛), sijeon(市廛), peongsisuh(平市署), nanjeon(亂廛), and the distribution, size and prosperity and decline of the border markets of the northern frontier such as the hoeryungkaesi(會寧開市) and geongwonkaesi(慶源開市). Contents related to transport geography are the distribution and functions of government granaries etc. Obviously, this book contains detailed information on various aspects of Korean geography. If we try to understand the contents of this book from the framework of modern geographical classification schemes, the geographic information contained in the book assumes even greater significance. In sum one may conclude that this book, which the king kept by his side, contained useful geography related knowledge and necessary information, and was directly relevant to the administration of the country. It exerted immense influence on the contemporary intellectual world of Joseon Korea, and was regarded as an invaluable resource.

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Analysis on Bond Characteristics of Reinforcements for UHPC Hybrid Cable-Stayed Bridge Deck Joints (초고성능 콘크리트 하이브리드 사장교 바닥판 접합부 철근의 부착 성능에 대한 해석)

  • Seonwoo, Yoon Ho;Park, Sung Kyun;Kwahk, Im Jong;Yoon, Young Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3A
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    • pp.207-214
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    • 2011
  • Ultra High Performance Concrete (UHPC), which is characterized by its high strength and advanced ductile behavior that is much superior to those of convention concrete, is a useful material to make thinner and longer bridges. The precast segmental construction method utilizing UHPC has been mainly studied because cast-in-place UHPC is very difficult and complicate to be achieved. As a part of those research, the structural performance evaluation of different types of joint connection method for hybrid cable-stayed bridge utilizing UHPC by using nonlinear analyses is performed in this study. The bond stress at joint is obtained by section force analyses for a 600 m cable-stayed bridge deck, and compared with the required bond stress at joint. Analysis results show that the U Type connection and straight type connection resist the highest ultimate load and bond strength, respectively. In addition, all considered joint connection systems satisfy the bond performances at joint required in the final stage of cable-stayed bridge utilizing UHPC.

High-Resolution MRI Study on Mouse Brain Using Micro-Imaging (초고해상도 미세영상 기법을 이용한 Mouse 뇌의 자기공명영상 연구)

  • Han, Doug-Young;Yoon, Moon-Hyun;Choe, Bo-Young
    • Investigative Magnetic Resonance Imaging
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    • v.12 no.2
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    • pp.142-147
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    • 2008
  • Purpose : By using the micro-imaging unit modified from NMR spectrometer, the high resolution MRI protocols of finer than 100 micron in 5 minutes, is sought for mouse, which plays a central role in animal studies Materials and Methods : C57BL/6 mouse, lighter than 50 gram, is used for the experiments. The superconducting magnet is vertical type with 89 mm inner diameter at 4.9 Tesla. The diameter of rf-coil is 30 mm. Mostly used techniques are the fast spin echo and the gradient echo pulse sequence. Results : For 2D images, proton density and T2 weighted images are obtained and their optimum experimental variables were sought. Minute structure of mouse brain can be recognized and 3D brain image is also obtained additionally. 3D image will be useful particularly for the dynamic contrast study using various contrast agents. Conclusion : Like the case of human and other small animals, the high resolution of mouse brain is enough to recognize the minute structure of it. Recently, similar studies are reported domestically, but it seems only a beginning stage. Due to easiness of breeding/control, mouse MRI study will soon play a vital part in brain study.

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Hypoglycemic Effect of the Giant Embryonic Rice Supplementation on Streptozotocin-induced Diabetic Rats (거대배아미 식이에 의한 Streptozotocin 유발 당뇨 흰쥐의 혈당강하 효과)

  • Lee, Youn-Ri;Nam, Seok-Hyun;Kang, Mi-Young
    • Korean Journal of Food Science and Technology
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    • v.38 no.3
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    • pp.427-431
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    • 2006
  • This study was performed to investigate the influence of giant embryo feeding on hypoglycemia in streptozotocin-induced diabetic rats. Streptozotocin -induced diabetic rats were fed four kinds of experimental diets such as corn starch diet as a control, polished rice diet, brown rice diet and giant embeyonic rice diet for 6 weeks. The body weight gain diabetic of control was signaficantly suppressed compared to that of the normal. The supplementation of giant embryo increased the surivival rate. Feeding of giant embryo appeared to have ameliorating effects on diabetic symptoms including features such as polyphasia, polyuria. Giant embryo shortened gastrointestinal transit time and increased total fecal weight, total fecal dry weight and fecal water content compared with diabetic control. Giant embryo showed fasting blood glucose lowering effect compared with diabetic control. The disaccharidase activities in proximal part of intestine such as maltase sucrase and lactase in giant embryo feeding groups were lower than diabetic control. The results of this study show that giant embryo supplementation may have a beneficial Veffect on the hypoglycemia may be useful in the diet therapy for diabetic.

A Study on the Design of Ergonomic Bridge Conning Display (인간공학적 Bridge Conning Display 설계에 관한 연구)

  • Yang Young-Hoon;Lee Bong-Wang;Lew Jae-Moon;Lee Chang-Min
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.11 no.2 s.23
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    • pp.33-40
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    • 2005
  • According to the development of technology of the navigational equipments, many bridge equipments have been improved, however, marine accidents by human error have not been reduced. Therefore, a matter of primary concern is focused on whether bridge equipments of ships are ergonomically arranged to reduce errors due to human factors. As part of a design of IBS(Integrated Bridge System) standard, rules of the conning display to save time and additional movements to obtain important informations of a ship should be established as soon as possible. In the present study, ergonomic design factors for the conning display are studied through the survey of related works, heuristic evaluations, sketch method tests as well as questionnaires. Using these factors, new conning display was designed and the ergonomic indices were evaluated by comparing tests of the existing conning displays. It is found that the designed conning display obtained high ergonomic index showed better performance, therefore, the ergonomic index studied in the present paper can be used as a useful design standard in the conning display design procedures.

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