• Title/Summary/Keyword: New Technology

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An Alternative Perspective to Resolve Modelling Uncertainty in Reliability Analysis for D/t Limitation Models of CFST (CFST의 D/t 제한모델들에 대한 신뢰성해석에서 모델링불확실성을 해결하는 선택적 방법)

  • Han, Taek Hee;Kim, Jung Joong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.4
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    • pp.409-415
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    • 2015
  • For the design of Concrete-Filled Steel Tube(CFST) columns, the outside diameter D to the steel tube thickness t ratio(D/t ratio) is limited to prevent the local buckling of steel tubes. Each design code proposes the respective model to compute the maximum D/t ratio using the yield strength of steel $f_y$ or $f_y$ and the elastic modulus of steel E. Considering the uncertainty in $f_y$ and E, the reliability index ${beta}$ for the local buckling of a CFST section can be calculated by formulating the limit state function including the maximum D/t models. The resulted ${beta}$ depends on the maximum D/t model used for the reliability analysis. This variability in reliability analysis is due to ambiguity in choosing computational models and it is called as "modelling uncertainty." This uncertainty can be considered as "non-specificity" of an epistemic uncertainty and modelled by constructing possibility distribution functions. In this study, three different computation models for the maximum D/t ratio are used to conduct reliability analyses for the local buckling of a CFST section and the reliability index ${beta}$ will be computed respectively. The "non-specific ${beta}s$" will be modelled by possibility distribution function and a metric, degree of confirmation, is measured from the possibility distribution function. It is shown that the degree of confirmation increases when ${beta}$ decreases. Conclusively, a new set of reliability indices associated with a degree of confirmation is determined and it is allowed to decide reliability index for the local buckling of a CFST section with an acceptable confirmation level.

A Study Of Design With Application On Of Gem Cutting Technique (보석 컷팅디자인을 활용한 보석산업활성화에 관한 연구)

  • Jang, Myeong Soo;Park, Seungchul
    • Journal of Digital Convergence
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    • v.10 no.10
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    • pp.483-490
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    • 2012
  • In parallel with advancement of the industrial society and accompanied quality-of-life improvement, jewelry is now rather viewed as one of common accessories used in daily life, than as a luxurious item as treated before change of perception about it in the past, attracting thus gradually multiplying demand for it. Thanks to rapid spread of multi media like the Internet, an increasing number of people have come to develop great liking for exceptional design and unique format of jewelry products. Following drain of their reserves, natural gems are unlikely to meet the demand for them fully in the future. As a consequence, it seems essential to rely on synthetic, artificial, imitation jewelry or organic substances and quasi-mineral in amorphous structure for substitute jewelry. Since synthetic jewelry has such a great potential as substitute jewelry, it is expected to maximize added value to jewelry if and when accompanied with development of creative design and upgrading of processing technology for jewelry, in addition to various types of synthetic jewelry and glass that have been already put in use as substitute substances. Synthetic jewelry is thus believed to be able to greatly contribute to progress of the jewelry industry. In many countries of the world, jewelry and gem industry has been regarded as one of promising sectors vital in enriching the national wealth. In this context, the Korean Ministry of Finance and Economy announced in July 2007 "an activating policy for the jewelry and gem industry, declaring to cultivate and grow it to be new engine for the nation's growth". The present paper thus aims to conduct a study exclusively on cutting design of synthetic jewelry as a part of measures to activate the jewelry industry in Korea. Efforts are made to develop designs for jewelry that are unique and different from the conventional stereotyped form of polishing and are added with color, pattern and fashionable cutting. Priority is given in this regard to designing jewelry that may attract general public and may be shared by public beyond the limit of conventional design for jewelry and producing products that stand in contrast with other products. By upgrading the quality of jewelry design, competitiveness of the jewelry industry may be ensured and the creative area of jewelry design may be expanded by far.

Crystal structure refinement and microwave dielectric characteristic of $(1-x)CaTiO_3-x(La_{1/3}Nd_{1/3})TiO_3$ ($(1-x)CaTiO_3-x(La_{1/3}Nd_{1/3})TiO_3$계의 결정구조 해석 및 마이크로파 유전 특성)

  • 조남웅;성경필;문종하;최주현
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.3
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    • pp.478-486
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    • 1998
  • $CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm x\le0.8)$ system was prepared by reaction of $CaCO_3,\;LaO_3,\;Nd_2CO_3$ and ,TEX>$TiO_2$ mixture at 1673 K, which can be applied for microwave dielectric ceramic materials. The lattice parameters of(1-x))$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm x\le0.8)$ system increased with the increase of x. Its structure was investigated by Rietveld profile-analysis of XRD in detail. Cations $ La^{3+}$ and Nd^{3+}$ were located at the $Ca^{2+}$ site in the range of $0\le \textrm x\le0.8$. crystal structure in $;(0\le \textrm x\le0.6)$ maintained space group Pnma with CaTiO_3 structure. The tiled and distorted $TiO_6$ was gradually released with the increase of x in $0\le \textrm x\le0.6$ .The structure was changed to a new space group of $Pmn2_1$ at the x value of 0.8. The relative dielectric constant $(\epsilon_r)$ of $(1-x)CaTiO_3-x(La_{1/3} Nd_{1/3})TiO_3$ ($(0\le \textrm x\le0.8)$) system was exponentially decreased by with the increased of x. The temperature coefficient of resonant frequency $(\tau_f)$ decreased with the increase of x in $0\le \textrm x\le0.6$ and then increased again at x=0.8 due to the change of crystal structure. The value of Q$\cdot f_o$ was 13800 (GHz) at x=0.2 and was very low under 2000 (GHz) in 0.4$\leq$x$\leq$0.8.

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A Study on the Work of Dental Hygienists by Service Area (치과위생사의 근무지별 업무실태에 관한 조사 연구)

  • Moon, Kyung-Sook;Hwang, Yoon-Sook;Kim, Young-Kyung;Jung, Jae-Yeon
    • Journal of Korean society of Dental Hygiene
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    • v.2 no.1
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    • pp.63-83
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    • 2002
  • The purpose of this study was to serve as a basis for more efficient dental hygienist human resources utilization and for determining some of the right directions for supplementary education for dental hygienists, by examining how they actually worked and what they thought of job-related things. The subjects in this study were 537 dental hygienists who participated in a seminar by the Korea Dental Hygienist Association. After a survey was conducted, the following findings were given: 1. 50.2% of the dental hygienists investigated completed legally required eight-class education. Those who worked in clinics took less supplementary education classes than the others in the other types of dental institutions. The main reason they didn't receive supplementary education was financial burden and uncooperative employers. 73.2% took supplementary education at the association or its branches. The association was most favored by those in clinical sector as a place that provides supplementary education, followed by its branch and university in the order named. And the dental hygienists in public health sector preferred university most, and the next best favored one was the association and its branch in the order named. Those in clinical sector hoped to acquire clinical information on patient management, implant or aesthetics, and the dental hygienists in public health sector wanted to learn about health administration, public oral health operations and oral health education, which were different from what those in clinical sector wanted. 2. Regarding the period of service, 492% had worked for three years or more. This fact suggested that their service term and average age continued to grow. And they thought they would decide the retirement time on their own. 3. The most common yearly income ranged from 12 million won to 16 million won(40.7%). For-those in clinics, yearly income was 14.36 million won, and that of the dental hygienists who had worked for less than 3 years was 12.90 million won. 4. The Korea Dental Hygienist Association was most required to protect the rights and interests of the members and offer new knowledge and technology. 5. The largest group of them were engaged in patient management, and this type of job also was the most favored one for them to do. The greatest number of the dental hygienists in public health sector were in charge of dental treatment. 6. Concerning their turnover rate, 492% had never changed their occupation. Specifically, 70.0% of the respondents who had worked for less than 3 years had have no experience to do that. The time constraints for self-development and conflicts with other workers were the cause of their turnover. Those in dental hospital and general hospital changed their occupation chiefly due to the lack of time for self-development, and for the dental hygienists in clinics, the conflicts with other workers were the main reason. The above-mentioned findings suggested that the way the dental hygienists looked at things was undergoing change. The service area made a difference to their preference for the type of supplementary education and institution in charge of it, as those in public health and clinical sectors had a different opinion. And the dental hygienists in clinical sector had a different opinion as well, according to service area, about salaries, reason of not taking supplementary education, preferred type of supplementary education, cause of turnover, and type of occupation to which they hoped to change employment. To utilize and supply human resources in a more stabilized manner, job description should be more segmented, standardized and classified clearly, and dental hygienists should be motivated to perform their substantial jobs, including oral disease prevention, oral prophylaxis and oral health education. To make it happen, it seems that dentists are required to have a clear understanding of dental hygienist job and to change the way they look at it.

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Changes and Improvements of the Standardized Eddy Covariance Data Processing in KoFlux (표준화된 KoFlux 에디 공분산 자료 처리 방법의 변화와 개선)

  • Kang, Minseok;Kim, Joon;Lee, Seung-Hoon;Kim, Jongho;Chun, Jung-Hwa;Cho, Sungsik
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.20 no.1
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    • pp.5-17
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    • 2018
  • The standardized eddy covariance flux data processing in KoFlux has been updated, and its database has been amended accordingly. KoFlux data users have not been informed properly regarding these changes and the likely impacts on their analyses. In this paper, we have documented how the current structure of data processing in KoFlux has been established through the changes and improvements to ensure transparency, reliability and usability of the KoFlux database. Due to increasing diversity and complexity of flux site instrumentation and organization, we have re-implemented the previously ignored or simplified procedures in data processing (e.g., frequency response correction, stationarity test), and added new methods for $CH_4$ flux gap-filling and $CO_2$ flux correction and partitioning. To evaluate the effects of the changes, we processed the data measured at a flat and homogeneous paddy field (i.e., HPK) and a deciduous forest in complex and heterogeneous topography (i.e., GDK), and quantified the differences. Based on the results from our overall assessment, it is confirmed that (1) the frequency response correction (HPK: 11~18% of biases for annually integrated values, GDK: 6~10%) and the stationarity test (HPK: 4~19% of biases for annually integrated values, GDK: 9~23%) are important for quality control and (2) the minimization of the missing data and the choice of the appropriate driver (rather than the choice of the gap-filling method) are important to reduce the uncertainty in gap-filled fluxes. These results suggest the future directions for the data processing technology development to ensure the continuity of the long-term KoFlux database.

Diagnostic assessment on vegetation damage due to hydrofluoric gas leak accident and restoration planning to mitigate the damage in a forest ecosystem around Hube Globe in Gumi (구미 휴브글로브 주변 삼림생태계에서 불화수소가스 유출 사고에 기인한 식생피해 진단 및 그 피해를 완화시키기 위한 복원 계획)

  • Kim, Gyung Soon;An, Ji Hong;Lim, Chi Hong;Lim, Yun Kyung;Jung, Song Hie;Lee, Chang Seok
    • Journal of Wetlands Research
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    • v.17 no.1
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    • pp.45-52
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    • 2015
  • We obtained the following results from investigation on vegetation damage from 5 to 6 August, 2013, about one year after an accident that hydrofluoric acid leaked from a chemical maker, Hube Globe in Gumi. Pinus densiflora and Pinus strobus showed very severe damage. Ginko biloba, Quercus acutissima, Pinus rigida, Salix glandulosa, Hibiscus syriacus, and Lagerstroemia indica showed severe damage. Quercus variabilis, Lespedeza cyrtobotrya, and Miscanthus sinensis showed moderate damage. Quercus aliena, Smilax china, Arundidinella hirta, Ailanthus altissima, Robinia pseudoacacia, and Paulowinia coreana showed slight damage. We did not find any plants without leaf damage around there. This result means that fluoride damage still persists in this area as was known that fluoride remains for a long time in air, soil and water and exerts negative effects at all levels of an ecosystem. In addition, fluoride content contained in plant leaf depended on the distance from a fertilizer producing factory and vegetation damage tended to proportionate to the concentration in the Yeocheon industrial complex. In these respects, a measure for removal or detoxification of the remaining fluoride is urgently required around the hydrofluoric acid leak spot. Fertilizing of dolomite containing Ca and Mg, which can trap fluoride, was prepared as one of the restoration plans. In addition, phosphate fertilizing was added in order to enhance soil ameliorating effects. Furthermore, we recommend the introduction of tolerant plants as the second measure to mitigate fluoride damage. As the tolerant plants to make a new forest by replacing trees died due to hydrofluoric acid gas damage, we recommended Q. aliena and S. china, A. hirta, etc. were recommended as plant species to add mantle vegetation to the forest margin to ensure stable interior environment of the forest.

Exploring the Use of Traditional Science Knowledge by 'Being a Commentator on Korean Traditional Science Culture' Activities (우리 과학 문화 해설사 되어보기 활동을 통한 전통 과학 지식의 교육적 활용 방안 탐색)

  • Lee, Jihye;Shin, Donghee
    • Journal of The Korean Association For Science Education
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    • v.37 no.1
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    • pp.193-214
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    • 2017
  • This study was carried out to identify the reality of students' understanding of Korean traditional scientific knowledge (TSK), the educational contexts influenced their understanding of TSK, and their sense of value of TSK, through the science activity 'Being a commentator on Korean traditional scientific culture' as a way of finding direction to apply TSK to science education while maintaining the inherent meaning of our traditional science. Seventh grade students have discovered TSK contents in Changdeok Palace, prepared their own scripts for seven months, and finally, explained to fifth to sixth grade students. The video recordings of all lessons, scripts of explanation, reports of field activities, and individual interviews were all analyzed. Students understood TSK in four viewpoints: the traditional view of nature, the traditional science and technology, the traditional life using science, and the natural science contents. During their activities, communication with peers or elders both in classroom and in Changdeok Palace, the interaction with place, and the sense of responsibility as a commentator helped students understand the scientific aspects of TSK, form contextual and sensible scientific knowledge, and apprehend various scientific explanations of contents. Depending on their internalization of experiences, the students' experiences produced three types of interpretation: delivery, persuasion, and understanding. Students formed their TSK sense of value as scientific characteristics, the need of new perspective about science, the need to protect and maintain TSK as our culture. The results of this study show that TSK can provide integrated and actual contextual education in science education and can be used to understand the cultural diversity of scientific and scientific methods and the characteristics of oriental scientific thinking. In addition, the simultaneous approach of TSK and school science to traditional culture can contribute to ideal concept formation and subjective attitude toward our traditional culture.

Fermentation characteristics of mulberry (Cudrania tricuspidata) fruits produced using microbes isolated from traditional fermented food, and development of fermented soybean food (전통장류로부터 분리한 발효미생물을 이용한 꾸지뽕 열매 발효물의 특성 및 장류제품 개발)

  • Lee, Eun-Sil;Jo, Seung-Wha;Yim, Eun-Jung;Kim, Yun-Sun;Park, Hae-Suk;Kim, Myung-Kon;Cho, Sung-Ho
    • Food Science and Preservation
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    • v.21 no.6
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    • pp.866-877
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    • 2014
  • The aim of this study was to develop a new functional traditional fermented soybean food using Cudrania tricuspidata fruits and fermentation microbes isolated from traditional fermented food. Aspergillus oryzae koji, Lactobacillus sp., and Bacillus sp. were used for the selection of a suitable microbe for the fermentation of Cudrania tricuspidata fruits, and as a result, Bacillus licheniformis SCDB 1234 was selected. SCDB 1234 enhanced the concentration of kaempferol in the Cudrania tricuspidata fruits from 9.54 to $217.04{\mu}g/g$ (about 22 times). The DPPH radical scavenging activity of the fermented materials was similar to that of BHA and BHT (92~99 ppm). The tyrosinase inhibitory activity was high with arbutin (95 ppm) and kojic acid (90 ppm). Doenjang-added fermentation materials of the Cudrania tricuspidata fruits were developed, and the organic acid, reducing sugar, and free amino acid of the developed Doenjang were analyzed. The pancreatic lipase inhibitory (PLI) activity and ${\alpha}$-glucosidase inhibitory (AGI) activity of the fermentation materials of the Cudrania tricuspidata fruits and the developed Doenjang were investigated, and it was found that after fermentation, the PLI and AGI activities of the fermentation materials of the Cudrania tricuspidata fruits were higher than those before fermentation, and that the AGI activity of the developed Doenjang after aging ($91.25{\pm}0.04%$) was higher than that before aging ($84.89{\pm}0.08%$).

0.1 MW Test Bed CO2 Capture Studies with New Absorbent (KoSol-5) (신 흡수제(KoSol-5)를 적용한 0.1 MW급 Test Bed CO2 포집 성능시험)

  • Lee, Junghyun;Kim, Beom-Ju;Shin, Su Hyun;kwak, No-Sang;Lee, Dong Woog;Lee, Ji Hyun;Shim, Jae-Goo
    • Applied Chemistry for Engineering
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    • v.27 no.4
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    • pp.391-396
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    • 2016
  • The absorption efficiency of amine $CO_2$ absorbent (KoSol-5) developed by KEPCO research institute was evaluated using a 0.1 MW test bed. The performance of post-combustion technology to capture two tons of $CO_2$ per day from a slipstream of the flue gas from a 500 MW coal-fired power station was first confirmed in Korea. Also the analysis of the absorbent regeneration energy was conducted to suggest the reliable data for the KoSol-5 absorbent performance. And we tested energy reduction effects by improving the absorption tower inter-cooling system. Overall results showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate : 90%) suggested by IEA-GHG. Also the regeneration energy of the KoSol-5 showed about $3.05GJ/tonCO_2$ which was about 25% reduction in the regeneration energy compared to that of using the commercial absorbent MEA (Monoethanolamine). Based on current experiments, the KoSol-5 absorbent showed high efficiency for $CO_2$ capture. It is expected that the application of KoSol-5 to commercial scale $CO_2$ capture plants could dramatically reduce $CO_2$ capture costs.

A Multimodal Profile Ensemble Approach to Development of Recommender Systems Using Big Data (빅데이터 기반 추천시스템 구현을 위한 다중 프로파일 앙상블 기법)

  • Kim, Minjeong;Cho, Yoonho
    • Journal of Intelligence and Information Systems
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    • v.21 no.4
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    • pp.93-110
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    • 2015
  • The recommender system is a system which recommends products to the customers who are likely to be interested in. Based on automated information filtering technology, various recommender systems have been developed. Collaborative filtering (CF), one of the most successful recommendation algorithms, has been applied in a number of different domains such as recommending Web pages, books, movies, music and products. But, it has been known that CF has a critical shortcoming. CF finds neighbors whose preferences are like those of the target customer and recommends products those customers have most liked. Thus, CF works properly only when there's a sufficient number of ratings on common product from customers. When there's a shortage of customer ratings, CF makes the formation of a neighborhood inaccurate, thereby resulting in poor recommendations. To improve the performance of CF based recommender systems, most of the related studies have been focused on the development of novel algorithms under the assumption of using a single profile, which is created from user's rating information for items, purchase transactions, or Web access logs. With the advent of big data, companies got to collect more data and to use a variety of information with big size. So, many companies recognize it very importantly to utilize big data because it makes companies to improve their competitiveness and to create new value. In particular, on the rise is the issue of utilizing personal big data in the recommender system. It is why personal big data facilitate more accurate identification of the preferences or behaviors of users. The proposed recommendation methodology is as follows: First, multimodal user profiles are created from personal big data in order to grasp the preferences and behavior of users from various viewpoints. We derive five user profiles based on the personal information such as rating, site preference, demographic, Internet usage, and topic in text. Next, the similarity between users is calculated based on the profiles and then neighbors of users are found from the results. One of three ensemble approaches is applied to calculate the similarity. Each ensemble approach uses the similarity of combined profile, the average similarity of each profile, and the weighted average similarity of each profile, respectively. Finally, the products that people among the neighborhood prefer most to are recommended to the target users. For the experiments, we used the demographic data and a very large volume of Web log transaction for 5,000 panel users of a company that is specialized to analyzing ranks of Web sites. R and SAS E-miner was used to implement the proposed recommender system and to conduct the topic analysis using the keyword search, respectively. To evaluate the recommendation performance, we used 60% of data for training and 40% of data for test. The 5-fold cross validation was also conducted to enhance the reliability of our experiments. A widely used combination metric called F1 metric that gives equal weight to both recall and precision was employed for our evaluation. As the results of evaluation, the proposed methodology achieved the significant improvement over the single profile based CF algorithm. In particular, the ensemble approach using weighted average similarity shows the highest performance. That is, the rate of improvement in F1 is 16.9 percent for the ensemble approach using weighted average similarity and 8.1 percent for the ensemble approach using average similarity of each profile. From these results, we conclude that the multimodal profile ensemble approach is a viable solution to the problems encountered when there's a shortage of customer ratings. This study has significance in suggesting what kind of information could we use to create profile in the environment of big data and how could we combine and utilize them effectively. However, our methodology should be further studied to consider for its real-world application. We need to compare the differences in recommendation accuracy by applying the proposed method to different recommendation algorithms and then to identify which combination of them would show the best performance.