• Title/Summary/Keyword: 상태유지

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Sorption Studies of $Cd^{2+}$ on Calcite: Kinetics and Reversibility (방해석의 $Cd^{2+}$ 흡착현상에 대한 연구)

  • Yoon, Hyeon;Reeder, Richard J.
    • Journal of the Mineralogical Society of Korea
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    • v.15 no.2
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    • pp.104-113
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    • 2002
  • The sorption of Cd$^{2+}$ on calcite was studied in aqueous solutions of several electrolytes. The Cd$^{2+}$ concentration, 10$^{-8}$ M, was kept well below saturation with respect to CdCO$_3$(s). Sorption behavior of Cd$^{2+}$ in different ionic strengths of NaClO$_4$solutions shows that sorption is independent of ionic strength. This result suggests that Cd$^{2+}$ sorption on calcite surface is of a specific nature, and adsorption is controlled by an inner-sphere type of surface complex. Two stages in the sorption behavior could be identified: an initial rapid uptake, followed by slower uptake reaching a maximum steady state by 145 hrs. No evidence was observed for surface precipitation, although it can not be entirely ruled out. Desorption of Cd$^{2+}$ from the calcite surface after resuspension into Cd-free solution is initially very rapid, but depends partly on the previous sorption history. Desorption behavior of Cd$^{2+}$ show that an initial rapid desorption followed either by slow uptake reaching a maximum, as in the adsorption experiments, or slowing desorption to reach a steady state minimum. This irreversible behavior of Cd$^{2+}$ sorption and desorption may act as one of the controls for regulating the mobility of dissolved Cd$^{2+}$ natural aqueous systems. Calculated adsorption partition coefficients suggest that overall sorption and desorption process in the concentration range are controlled by d single mechanism.ingle mechanism.

Study of CO2 Carbonation-Regeneration Characteristics of Potassium-Based Dry Sorbents According to Water Vapor Contents of Inlet Gas and Regeneration Temperature in the Cycle Experiments of Bubbling Fluidized-Bed Reactor (회분식 기포유동층 반응기에서 K-계열 건식흡수제의 주입수분농도 및 재생반응온도에 따른 CO2 흡수-재생 반응특성 연구)

  • Park, Keun-Woo;Park, Yeong Seong;Park, Young Cheol;Jo, Sung-Ho;Yi, Chang-Keun
    • Korean Chemical Engineering Research
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    • v.47 no.3
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    • pp.349-354
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    • 2009
  • In this study, a bubbling fluidized-bed reactor was used to study $CO_2$ capture from flue gas using a potassium-based dry sorbent. A dry sorbent, manufactured by the Korea Electric Power Research Institute, consists of 35% of $K_2CO_3$ for $CO_2$ absorption and 65% of supporters for mechanical strength. $H_2O$, a reactant of the carbonation reaction, was supplied in the reactor as a form of saturated water vapor at a given temperature. The experiment of the regeneration reaction was performed by raising up to a given temperature using $N_2$ as a fluidization gas. It was indicated that sorption capacity and regenerability of dry sorbents showed high-efficiency at $1.97\;mol\;H_2O/mol\;CO_2$ and $400^{\circ}C$, respectively. The regenerated sorbent samples were analyzed by TGA to confirm the extent of the reaction. When the regeneration temperature was $150^{\circ}C$, the regenerability of dry sorbents was about 60%, which was capable of applying those sorbents to a two-interconnected fluidized-bed reactor system with continuous solid circulation. The results obtained in this study can be used as basic data for designing and operating a large scale $CO_2$ capture process with two fluidized-bed reactors.

Design of a Crowd-Sourced Fingerprint Mapping and Localization System (군중-제공 신호지도 작성 및 위치 추적 시스템의 설계)

  • Choi, Eun-Mi;Kim, In-Cheol
    • KIPS Transactions on Software and Data Engineering
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    • v.2 no.9
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    • pp.595-602
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    • 2013
  • WiFi fingerprinting is well known as an effective localization technique used for indoor environments. However, this technique requires a large amount of pre-built fingerprint maps over the entire space. Moreover, due to environmental changes, these maps have to be newly built or updated periodically by experts. As a way to avoid this problem, crowd-sourced fingerprint mapping attracts many interests from researchers. This approach supports many volunteer users to share their WiFi fingerprints collected at a specific environment. Therefore, crowd-sourced fingerprinting can automatically update fingerprint maps up-to-date. In most previous systems, however, individual users were asked to enter their positions manually to build their local fingerprint maps. Moreover, the systems do not have any principled mechanism to keep fingerprint maps clean by detecting and filtering out erroneous fingerprints collected from multiple users. In this paper, we present the design of a crowd-sourced fingerprint mapping and localization(CMAL) system. The proposed system can not only automatically build and/or update WiFi fingerprint maps from fingerprint collections provided by multiple smartphone users, but also simultaneously track their positions using the up-to-date maps. The CMAL system consists of multiple clients to work on individual smartphones to collect fingerprints and a central server to maintain a database of fingerprint maps. Each client contains a particle filter-based WiFi SLAM engine, tracking the smartphone user's position and building each local fingerprint map. The server of our system adopts a Gaussian interpolation-based error filtering algorithm to maintain the integrity of fingerprint maps. Through various experiments, we show the high performance of our system.

A Correlation Between Vertical Fixation Disparity and Stereopsis at Near (근거리에서 수직주시시차와 입체시와의 관계)

  • Yoon, Min-Hwa
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.3
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    • pp.321-327
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    • 2013
  • Purpose: To investigate a correlation between vertical fixation disparity and stereopsis by analyzing distribution of types of vertical fixation disparity. Methods: In this study, RANDOT(R) stereotest partly using random dot was used in stereopsis tests. The vertical fixation disparity in close proximity categorized fixation disparity slope into six types on the basis of the result of measurement in when two thin lines, one for one eye looks, become overlapped as a line by adding into prism with Wesson fixation disparity card while maintaining a distance of 25 cm from patients. Results: In the types of near vertical fixation disparity curve, targeting 43 people, the first type 55.82% was the most distributed, the second type is the least 23.25%, the third type of 4.65%, the fourth type of 4.65%, the fifth type of 6.98%, the sixths types of 4.65% were distributed. The result of a correlation analysis, which shows the degree of linear correlation between two variables, represented that stereopsis is not correlated with Y-intercept (r = -0.07) which show vertical fixation disparity, associated phoria (r = -0.03) and dissociated phoria (r = -0.00), but it was not statistically significant (p>0.05). Fixation disparity slope of vertical fixation disparity (r = 0.36) was shown to have a positive correlation with stereopsis. It has a low positive correlation and a meaningful statistics (p<0.05). The Y-intercept which indicates vertical fixation disparity was also not associated with stereopsis (r = -0.07) and dissociated phoria (r = -0.03), and this was not statistically significant (p>0.05), while it had a high correlation as well as a statistically significant with associated phoria (r = 0.89). There was a negative correlation between Y-intercept and fixation disparity slope of vertical fixation disparity (r = -0.33). It showed a low relationship but statistically valuable (p>0.05). As a result of regression analysis, the stereopsis was changed as 7.631" if vertical fixation disparity changes 1' and the vertical fixation disparity changed as 0.017' if stereopsis changes 1', and the change was statistically significant (p<0.05). Conclusions: The study shows that there is a low correlation between stereopsis and vertical fixation disparity, and it is difficult to determine stereopsis only using vertical fixation disparity. Therefore, it suggests other factors above vertical fixation disparity have greater influence on stereopsis.

Evaluation of Importance and Performance for Students and Employees about Sanitary Characteristics for High School Foodservice in Busan (부산지역 고등학교 학생과 급식종사자의 급식위생에 대한 중요도와 수행도 평가)

  • Kim, So-Hee
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.9
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    • pp.1414-1426
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    • 2005
  • The evaluation of students and employees on the importance and the performance for sanitary characteristics in high school foodservices, was investigated. The questionnaires were administered to 379 students and 141 employees in 13 high school, in Busan and then the data evaluated by 5 scales method of Likert were statistically analyzed. The mean scores of the importance and the performance evaluated by students (4.26/3.24) were significantly (p<0.01) lower than those by employees (4.71/4.51). Both the students and the employees percepted that, among sanitary characteristics, cleanliness of meals was most important. The student assessed the performance of withdrawal of plate waste as lowest scores, however the employees assessed student's hygiene as lowest scores, among sanitary characteristics. The gap score of the student (-1.02) between the importance and performance for sanitary factor was higher than that of the employees (-0.02) in high school foodservice. The importance grid of students and employees revealed that the items of tray cleanliness, dining table cleanliness, restaurant cleanliness, and handwashing before serving were high scores to the students, but low scores to the employees. The performance grid of students and employees revealed that the items of tray cleanliness, dining table cleanliness, restaurant cleanliness, the sanitation of treatment process of Plate waste, cleanliness of utensils of platewaste, not touch utensils before serving, handwashing before serving, handwashing before eating and not touch inside of tray were low scores to both the students and the employees. Therefore, it is suggested that the sanitary operations for dining place, treatment process of plate waste and the student's hygiene might have to increase in high school foodservice.

The Development of Differentiating Method between Fresh and Frozen Beef by Using the Mitochondrial Malate Dehydrogenase Activity (Mitochondrial Malate Dehydrogenase 활성을 이용한 냉장우육과 냉동우육의 판별법 개발)

  • Han, Kyu-Ho;Kim, Nam-Kyu;Lee, Si-Kyung;Cho, Jin-Kook;Choi, Kang-Duk;Jeons, You-Jin;Lee, Chi-Ho
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.10
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    • pp.1599-1605
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    • 2005
  • The object of this study is to develop the method for differentiating fresh meat from frozen meat by using the measurement of the mitochondrial malate dehydrogenase in the Korean native cattle. The principle of this experiment is based on the fact that the enzyme proteins associated with mitochondrial membrane could be released by freezing. The methods of differentiating fresh meat from thawed, frozen meat were studied by measurements of mitochondrial malate dehydrogenase activity of meat press juice. Fresh and frozen beef were stored at 4, -4, -18 and -77$^{\circ}C$ for 15-day storage period. A meat press machine using air pressure was manufactured especially for these experiments, and sufficient amount of drip (about 0.15 mL/g) from 1.5 g of beef sample was efficiently obtained under a pressure of 8 kg/$cm^{2}$ generated by the meat pressing machine. The mitochondrial malate dehydrogenase activities of frozen meat drip i년ices stored at -18 and -77$^{\circ}C$ were significantly higher than those of fresh and frozen meat samples at -4$^{\circ}C$ (p < 0.05) during 10-min reaction period. However, the enzyme activities of the frozen meat drip juices (-18 and -77$^{\circ}C$) disappeared after 5 minutes of the reaction, which was not observed from the fresh and -4$^{\circ}C$ frozen meats. The enzyme activity maintained until 12 minutes for the fresh and -4$^{\circ}C$ frozen meats. From these results, the mitochondrial malate dehydrogenase could be considered as an indicator to differentiate fresh beef from frozen one.

Studies on Epicotyl Grafting of Hardwood Scion of Walnut (호도(胡桃)나무 유태접목(幼台接木)에 관(関)한 연구(硏究))

  • Kim, Su In
    • Journal of Korean Society of Forest Science
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    • v.55 no.1
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    • pp.68-75
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    • 1982
  • This study was carried out to promote percent survival of the walnut seedling grafting. The hardwood scions of the walnut were grafted on the nures seed-stock of the Juglans mandshurica Mat in an electric heating bed, then planted in field. The results obtained from the study were as follows : The optimum time of scion cpllection was from January to February. The best medium of the seed bed was sandy soil. The best grafting time was form the early to the 20the of the march. When the grafted seedling in the heating bed was trans-planted on filed 90percent of the seedlings was survived until autmn. The percent grafting on the elective heating bed was 90%. Crown gall occuring frequently in chestnut nurse graft was not appeared in juglans mandshurica Max grafted seedling of after outplanting. The grafted seedlings have not shown any physiological defects but developed normaly 3 years since grafting.

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Economic Welfare Study on Seasonal and Time Period Electricity Pricing (계시별 전력가격에 대한 경제적 후생 연구)

  • Yoo, Young-Hoon;Kim, SungSoo
    • Environmental and Resource Economics Review
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    • v.14 no.2
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    • pp.519-547
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    • 2005
  • The aim of this study is to analysis how economic welfare lost happens within the present korea seasonal and time period electricity pricing system and find out reasonable electricity price system acceptable during the transitional period of korea electricity industry restructuring To analyze economic welfare lost in the electricity industry, in advance seasonal and time periodic 9 demand curves(summer, spring &fall, winter/peak-load time, middle-load time, low-load time) and one market supply curve are made and then using these demand and supply curve, seasonal and time periodic market equilibrium prices is calculated. Finally, comparing these market equilibrium prices with present regulated classified seasonal and time periodic prices, the whole economic welfare lost in the electricity industry is calculated. The result of this study shows that in 2002, the total economic welfare lost in electricity industry is 137,770 million Won and under present price system, the worst welfare lost is happening seasonally in spring & fall, time periodically in the middle-load time. Specifically analyzing the characteristics of welfare lost, especially on the industry customers and service customers which are applied in seasonal and time periodic pricing, for the industry customers, the welfare lost calculated in this class occupies 51% of the total welfare lost in the whole electricity industry and the worst welfare lost is happening seasonally in spring & fall, time periodically in the middle-load time. For service customers, the welfare lost calculated in this class occupies 13% of the total welfare lost in the whole electricity industry and the worst welfare lost is happening seasonally in summer, time periodically in the peak time Finally, this study was made based on the year of 2002 and KEPCO has practiced two times of rate change until now. The result of rate change was positively analyzed in the direction of economic welfare improvement(welfare improvement achieved by 16.3% compared to 2002 result).

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Application Study of $CO_2$ Snow Cleaning for Cleaning of Foreign Matter and Corrosion Products on Iron Artifacts ($CO_2$ Snow Cleaning 적용 철제유물 표면 이물질 제거 연구)

  • Lee, Eun-Ji;Cho, Nam-Chul;Lee, Jong-Myong;Yu, Jae-Eun
    • Journal of Conservation Science
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    • v.27 no.3
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    • pp.333-344
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    • 2011
  • Cleaning of foreign matter and corrosion products on surface among conservation treatment of iron artifacts is an important part for looking up a original form. The sand blaster is the most popular equipment when it removes the foreign matter and corrosion products on iron artifacts surface. Current foreign matter and corrosion products equipment, which mostly uses, is sand blaster. Glass dust which sprayed from sand blaster is harmful and causing environmental pollution. In order to solve these problems, we investigated the $CO_2$ snow cleaning that use a eco-friendly equipment to apply for cleaning foreign matter and corrosion products on surface of iron artifacts. It examined by using sand blaster and $CO_2$ snow cleaning to aged steel coupon and iron artifacts. In case of aged steel coupon, the result showed that the sand blaster and $CO_2$ snow cleaning methods were similar to the degrees of cleaning foreign matter and corrosion products, through surface roughness, color measurement and SEM. $CO_2$ snow cleaning applied to aged steel coupons weren't worn out the surface in comparison with sand blaster by SEM. When applied to the iron artifacts, power nozzle of the $CO_2$ snow cleaning was an excellent cleaning effect that surface wern't worn out in comparison with sand blaster. And, it showed that internal structure change of metal was no found before and after cleaning by X-ray radiography. Consequently, we confirmed that cleaning of the sand blaster and power nozzle of $CO_2$ snow cleaning were similar to the effect. But, it's very careful to use this method because of high outlet pressure of power nozzle for applying to the iron artifacts. As a result of experiments, it could be found that the cleaning methods should be selected depending on internal state of the artifacts.

Study on the Re-corrosion Characteristics of Corrosion Products by Weeping of Iron Artifacts (철제유물 Weeping에 따른 부식화합물의 재부식 특성 연구)

  • Park, Hyung-Ho;Lee, Hye-Youn;Lee, Jae-Sung;Yu, Jae-Eun
    • Journal of Conservation Science
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    • v.29 no.3
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    • pp.287-296
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    • 2013
  • Excavated iron objects are preserved in stable condition through processes of conservation treatment because they are found in the form of various corrosion products. However, the conservation treatment leads to re-corrosion over time and accordingly, iron objects can be severely damaged, and therefore fundamental measures need to be prepared to control it. In this study, the types and characteristics of corrosion products were scientifically analyzed according to the re-corrosion of iron artifacts. In addition, the stability of the corrosion products was evaluated by exposing the standard samples under the re-corrosion environment. Re-corrosion proceeded with weeping in reddish brown on the cracks of iron artifacts. Weeping was detected akagan$\acute{e}$ite had a low hydrogen ion concentration and high chloride ion. The selection of standard sample goethite, lepidocrocite, hematite, and magnetite, were evaluated corrosive by weeping. After the samples were immersed in HCl(pH 1), $H_2SO_4$(pH 1), $H_2O$(pH 6) solution, they had been maintained for 180 days in relative humidity of 20%, 50%, 80% to investiage the changes of chemical components. As a result of analysis, the changes of chemical components were not showed in goethite, lepidocrocite, and hematite. But magnetite was changed to lepidocrocite in solution including chloride ion($Cl^-$) and to goethite and lepidocrocite solution including sulfuric acid($SO{_4}^{2-}$). Results of the study, in the case of magnetite known as s stable corrosion compound, it was identified the corrosion of magnetite occurs by corrosive ions, which means weeping generated in the iron artifacts can corrode magnetite as well as base metal.