• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.307-323
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• 2018

The Inseong Au-Ag and base metal deposit, located in Chungchengbuk-do, Korea, consists of series of quartz veins filling fissures. The deposit occurs in Hwanggangri meta-sediment formation, a lime pebble-bearing phyllite, in the Okcheon Supergroup. Abundant ore minerals in the deposit are pyrite, arsenopyrite, sphalerite, chalcopyrite and galena. The gangue minerals are quartz, calcite and chlorite. Hydrothermal alteration such as chlorization, silicitication, sericitization and carbonitization can be observed around the quartz veins. 4 vein stages can be distinguished based on its paragenetic sequence, vein structure, alteration features and ore minerals. Microthermometry of the fluid inclusion assemblages occur in the veins are conducted to reconstruct a hydrothermal P-T evolution. Fluid inclusions in clean and barren quartz vein in stage 1 have Th of $270{\sim}342^{\circ}C$ and salinity of 1.7~6.4 (NaCl eqiv.) wt%. Euhedral quartz crystal in stage 2 have Th of $108{\sim}350^{\circ}C$ and salinity of 0.5~7.5 wt%. Barren milky quartz vein in stage 3 have Th of $174{\sim}380^{\circ}C$ and salinity of 0.8~7.5 wt%. Calcite vein in stage 4 have Th of $103{\sim}265^{\circ}C$ and salinity of 0.7~6.4 wt%. Calculated paleodepth about 0.5~1.5 km (hydrostatic pressure) indicate epithermal ore-forming condition. Shallow depth but relatively high-T hydrothermal fluids possibly create a steep geothermal gradient, sufficient for base metal precipitation in the Inseong deposit.

• Journal of Dairy Science and Biotechnology
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• v.37 no.2
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• pp.115-128
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• 2019

Lactic acid bacteria obtained from traditional Kimchi were selected on the basis of their caseinolytic activity and lactose usability and examined for availability as a starter in probiotic activity. Thirty-two strains were selected as lactic acid producing bacteria in BCP agar, and two strains (KC23 and KF26) with more than 90% resistance for both acid and bile salts were selected. The two strains were identified as L. plantarum (KC23) and L. paracasei (KF26) by API 50 CHL system and 16S rRNA sequence analysis. L. plantarum (KC23) was finally selected based on its biochemical characteristics for lactose and raffinose usability. Free tyrosine content increased rapidly in 10% skimmed milk medium, from $24.1{\mu}g/mL$ after 8 h to $43.9{\mu}g/mL$ after 16 h. Additionally, the caseinolytic clear zone of 12 mm of L. plantarum (KC23) was greater than the 9 mm zone of commercial L. acidophilus CSLA. The bacterium exhibited mesophilic growth and yielded $8.9{\times}10^8CFU/mL$ when incubated at $37^{\circ}C$ for 12 h at pH 4.25. Moreover, L. plantarum KC23 exhibited antibacterial activity as it formed a clear zone of 8-13 mm for the 5 pathogens. Adherent activity was 2.23 fold higher than that of LGG. The acidity of 10% skimmed milk fermented for 12 h was 0.74%.

• Journal of Global Scholars of Marketing Science
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• v.19 no.3
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• pp.49-61
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• 2009

This article provides training exercises for executives into interpreting subroutine maps of executives' thinking in processing business and industrial marketing problems and opportunities. This study builds on premises that Schank proposes about learning and teaching including (1) learning occurs by experiencing and the best instruction offers learners opportunities to distill their knowledge and skills from interactive stories in the form of goal.based scenarios, team projects, and understanding stories from experts. Also, (2) telling does not lead to learning because learning requires action-training environments should emphasize active engagement with stories, cases, and projects. Each training case study includes executive exposure to decision system analysis (DSA). The training case requires the executive to write a "Briefing Report" of a DSA map. Instructions to the executive trainee in writing the briefing report include coverage in the briefing report of (1) details of the essence of the DSA map and (2) a statement of warnings and opportunities that the executive map reader interprets within the DSA map. The length maximum for a briefing report is 500 words-an arbitrary rule that works well in executive training programs. Following this introduction, section two of the article briefly summarizes relevant literature on how humans think within contexts in response to problems and opportunities. Section three illustrates the creation and interpreting of DSA maps using a training exercise in pricing a chemical product to different OEM (original equipment manufacturer) customers. Section four presents a training exercise in pricing decisions by a petroleum manufacturing firm. Section five presents a training exercise in marketing strategies by an office furniture distributer along with buying strategies by business customers. Each of the three training exercises is based on research into information processing and decision making of executives operating in marketing contexts. Section six concludes the article with suggestions for use of this training case and for developing additional training cases for honing executives' decision-making skills. Todd and Gigerenzer propose that humans use simple heuristics because they enable adaptive behavior by exploiting the structure of information in natural decision environments. "Simplicity is a virtue, rather than a curse". Bounded rationality theorists emphasize the centrality of Simon's proposition, "Human rational behavior is shaped by a scissors whose blades are the structure of the task environments and the computational capabilities of the actor". Gigerenzer's view is relevant to Simon's environmental blade and to the environmental structures in the three cases in this article, "The term environment, here, does not refer to a description of the total physical and biological environment, but only to that part important to an organism, given its needs and goals." The present article directs attention to research that combines reports on the structure of task environments with the use of adaptive toolbox heuristics of actors. The DSA mapping approach here concerns the match between strategy and an environment-the development and understanding of ecological rationality theory. Aspiration adaptation theory is central to this approach. Aspiration adaptation theory models decision making as a multi-goal problem without aggregation of the goals into a complete preference order over all decision alternatives. The three case studies in this article permit the learner to apply propositions in aspiration level rules in reaching a decision. Aspiration adaptation takes the form of a sequence of adjustment steps. An adjustment step shifts the current aspiration level to a neighboring point on an aspiration grid by a change in only one goal variable. An upward adjustment step is an increase and a downward adjustment step is a decrease of a goal variable. Creating and using aspiration adaptation levels is integral to bounded rationality theory. The present article increases understanding and expertise of both aspiration adaptation and bounded rationality theories by providing learner experiences and practice in using propositions in both theories. Practice in ranking CTSs and writing TOP gists from DSA maps serves to clarify and deepen Selten's view, "Clearly, aspiration adaptation must enter the picture as an integrated part of the search for a solution." The body of "direct research" by Mintzberg, Gladwin's ethnographic decision tree modeling, and Huff's work on mapping strategic thought are suggestions on where to look for research that considers both the structure of the environment and the computational capabilities of the actors making decisions in these environments. Such research on bounded rationality permits both further development of theory in how and why decisions are made in real life and the development of learning exercises in the use of heuristics occurring in natural environments. The exercises in the present article encourage learning skills and principles of using fast and frugal heuristics in contexts of their intended use. The exercises respond to Schank's wisdom, "In a deep sense, education isn't about knowledge or getting students to know what has happened. It is about getting them to feel what has happened. This is not easy to do. Education, as it is in schools today, is emotionless. This is a huge problem." The three cases and accompanying set of exercise questions adhere to Schank's view, "Processes are best taught by actually engaging in them, which can often mean, for mental processing, active discussion."

• Journal of Korean Society of Forest Science
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• v.34 no.1
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• pp.31-46
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• 1977

The study was made to give some helpful information for policy-making on ornamental tree cultivation by doing a survey on general situations, management analysis, and future prospects of the ornamental tree growing. The study was carried out through literature studies related to the subject, questionaire surveys, and on-the-spot investigation. The questionaire surveys could be divided into two parts: pre-questionaire survey and main-questionaire survey. In the pre-questionaire survey, the researchers intended to identify the total number of ornamental tree growers, cultivation areas in size and their locations. The questionaires were sent to each town and county administration authorities, forest cooperatives, and related organizations through-out the nation. The main-questionaires were prepared for detailed study and the questionaires were sent to 200 tree growers selected by option by taking considerations of the number of tree growers and the size of cultivating areas in regions. The main findings and some information obtained in the survey were as follows: 1. The total land for ornamental tree growing was amounted to 1,873.02 hectares and the number of cultivators was totaled to 2,717. 2. The main occupations of the ornamental tree growers were found in horticulture (41.9%), agronomy (25.9%), officialdom (11.3%), animal husbandry (6.5%), business circle(4.8%), and forestry (3.2%) in sequence. 3. The ornamental trees were cultivated mostly upperland (54.8), forest land (19.4%), rice paddy (11.3%) and others. 4. The educational training of the tree growers seemed quite high. The results of the survey indicated that a large number of tree growers was occupied by college graduates (38.7%), and then high school graduates (34.7%), middle school graduates (12.9%) in order. 5. The tree farming was undertaken as a side-job (41.9%) rather than main-job (23.4%), but a few of respondents rated as subsidiary-job (18.6%). 6. The management status classified by the rate of hired labors used was likely to belong to three categories: independant enterprise management (41.9%); half independant management (31.5%); and self-management (32.4%). 7. The majority of the tree growers sold their products to the consumers through middle-man channel (48.4%), or directly to the house-holder and detailers (13.7%), but a few of the respondents answered that they disposed of their products by bidding (11.2%) or by direct selling to the contractors (4.8%). 8. The channel cf marketing seemed somewhat complicated. The results of the survey were as: (1) producers ${\rightarrow}$consumers (22.6%) (2) producers ${\rightarrow}$field middle-men${\rightarrow}$consumers (33.1%) (3) producers ${\rightarrow}$field middle-men${\rightarrow}$first stage brokers${\rightarrow}$consumers (15.3%) (4) producers ${\rightarrow}$field middle-men${\rightarrow}$second stage middle-men${\rightarrow}$brokers${\rightarrow}$consumers (5.7%) (5) producers${\rightarrow}$field middle-men${\rightarrow}$third stage middle-men${\rightarrow}$second stage middlemen${\rightarrow}$brokers${\rightarrow}$consumers (4.8%) 9. It was responded that the margin for each stage of middle-men or brokers was assumed to be 30-50%(33.1%), 20-30%(32.3%), 50-100%(9.7%), and 100-200%(2.4%) in sequence. 10. The difference between the delivery price of consumers and field selling price of the producers seemed quite large. Majority of producers responded that they received half a price compared to the consumer's prices. 11. About two thirds of the respondents opposed to the measure of "Law on Preservation and Utilization of Agricultural Land" in which says that all the ornamental trees grown on flat agricultural lands less than 8 degrees in slope must be transplanted within three years to other places more than 8 degrees in slope. 12. The tree growers said that they have paid rather high land taxes than they ought to pay (38.7%), but come responded that land tax seemed to be appropriate (15.3%), and half of the respondents answered "not known". 13. The measures for the standardization of ornamental trees by size were backed up by a large number of respondents (57.3%), but one third of the respondents showed negative answer (29.8%). 14. About half of the respondents favored the systematic marketing through organization such as forest cooperatives (54%), but quite a few respondents opposed to organizing the systematic marketing channel (36.3%). 15. The necessary measures for permission in ornamental tree cultivation was rejected by a large number of respondents (49.2%) than those of favored (43.6%).

• Journal of Intelligence and Information Systems
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• v.24 no.4
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• pp.111-136
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• 2018

In this paper, we propose a methodology to extract answer information about queries from various types of unstructured documents collected from multi-sources existing on web in order to expand knowledge base. The proposed methodology is divided into the following steps. 1) Collect relevant documents from Wikipedia, Naver encyclopedia, and Naver news sources for "subject-predicate" separated queries and classify the proper documents. 2) Determine whether the sentence is suitable for extracting information and derive the confidence. 3) Based on the predicate feature, extract the information in the proper sentence and derive the overall confidence of the information extraction result. In order to evaluate the performance of the information extraction system, we selected 400 queries from the artificial intelligence speaker of SK-Telecom. Compared with the baseline model, it is confirmed that it shows higher performance index than the existing model. The contribution of this study is that we develop a sequence tagging model based on bi-directional LSTM-CRF using the predicate feature of the query, with this we developed a robust model that can maintain high recall performance even in various types of unstructured documents collected from multiple sources. The problem of information extraction for knowledge base extension should take into account heterogeneous characteristics of source-specific document types. The proposed methodology proved to extract information effectively from various types of unstructured documents compared to the baseline model. There is a limitation in previous research that the performance is poor when extracting information about the document type that is different from the training data. In addition, this study can prevent unnecessary information extraction attempts from the documents that do not include the answer information through the process for predicting the suitability of information extraction of documents and sentences before the information extraction step. It is meaningful that we provided a method that precision performance can be maintained even in actual web environment. The information extraction problem for the knowledge base expansion has the characteristic that it can not guarantee whether the document includes the correct answer because it is aimed at the unstructured document existing in the real web. When the question answering is performed on a real web, previous machine reading comprehension studies has a limitation that it shows a low level of precision because it frequently attempts to extract an answer even in a document in which there is no correct answer. The policy that predicts the suitability of document and sentence information extraction is meaningful in that it contributes to maintaining the performance of information extraction even in real web environment. The limitations of this study and future research directions are as follows. First, it is a problem related to data preprocessing. In this study, the unit of knowledge extraction is classified through the morphological analysis based on the open source Konlpy python package, and the information extraction result can be improperly performed because morphological analysis is not performed properly. To enhance the performance of information extraction results, it is necessary to develop an advanced morpheme analyzer. Second, it is a problem of entity ambiguity. The information extraction system of this study can not distinguish the same name that has different intention. If several people with the same name appear in the news, the system may not extract information about the intended query. In future research, it is necessary to take measures to identify the person with the same name. Third, it is a problem of evaluation query data. In this study, we selected 400 of user queries collected from SK Telecom 's interactive artificial intelligent speaker to evaluate the performance of the information extraction system. n this study, we developed evaluation data set using 800 documents (400 questions * 7 articles per question (1 Wikipedia, 3 Naver encyclopedia, 3 Naver news) by judging whether a correct answer is included or not. To ensure the external validity of the study, it is desirable to use more queries to determine the performance of the system. This is a costly activity that must be done manually. Future research needs to evaluate the system for more queries. It is also necessary to develop a Korean benchmark data set of information extraction system for queries from multi-source web documents to build an environment that can evaluate the results more objectively.

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.32-51
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• 2016

This study examines, based on the database of the Institute for the Translation of Korean Classics(ITKC), the garden plants and their symbolism, and the landscape culture recorded in 'Jipkyungjaeyoungsi(the Series of Poems on Gardens Poetry)' in relevance to traditional houses. First, Jipkyungjaeyoungsi had been continuously written since mid-Goryeo dynasty, when it was first brought in, until the late Joseon dynasty. It was mainly enjoyed by the upper class who chose the path of civil servants. 33 pieces of Jaeyoungsi(題詠詩) in 25 books out of a total of 165 books are related to residential gardens. The first person who wrote a poem in relation to this is believed to be Lee GyuBo(1168~1241) in the late Goryeo dynasty. He is believed to be the first person to contribute to the expansion of natural materials and the variation of entertainment in landscape culture with such books as 'Toesikjaepalyoung(退食齋八詠)', 'Gabeunjeungyukyoung(家盆中六詠)'and 'Gapoyukyoung(家圃六詠)'. Second, most of the poems used the names of the guesthouses. Out of the 33 sections, 19(57.5%) used 8 yeong(詠), then it was in the sequence of 4 yeong(詠), 6 yeong, 10 yeong, 14 yeong, 15 yeong, 16 yeong, 36 yeong(詠) and so on. In the poem writing, it appears to break the patterns of Sosangpalkyung(瀟湘八景) type of writings and is differentiated by (1) focusing on the independent title of the scenery, (2) combining the names of the place and landscape, (3) focusing on the name of the landscape. Third, the subtitles were derived from (1) mostly natural landscape focused on nature and garden plants(22 sections, 66.7%), (2) cultural landscape focused on landscape facilities such as guesthouses, ponds and pavilions(3 sections), (3) complex cultural scenery focused on the activities of people in nature(8 sections). Residents enjoy not only their aesthetic preferences and actual view, but the ideation of the scenery. Especially, they display attachment to and preference for vegetables and herbs, which had been neglected. Fourth, the percentage of deciduous tree population(17 species) rated higher(80.9%) compared to the evergreens(4 species). These aspects are similar results with the listed rate in 'Imwonkyungjaeji(林園經濟志)' by Seo YuGu [evergreen 18 species(21.2%) and deciduous trees 67 species(78.8%)] and precedent researches [Byun WooHyuk(1976), Jung DongOh(1977), Lee Sun(2006)]. Fifth, the frequency of the occurrence of garden plants were plum blossoms(14 times), bamboos(14 times), pine trees(11 times), lotus(11 times), chrysanthemum(10 times), willows(5 times), pomegranates(4 times), maple trees(14 times), royal foxglove trees, common crapemyrtle, chestnut trees, peony, plantains, reeds and a cockscombs(2 times). Thus, the frequency were higher with symbolic plants in relations to (1) Confucian norms(pine trees, oriental arbor vitae, plum blossoms, chrysanthemums, bamboos and lotus), (2) living philosophy of sustain-ability(chrysanthemum, willow), (3) the ideology of seclusion and seeking peace of mind(royal foxglove ree, bamboo). Sixth, it was possible to trace plants in the courtyard and outer garden, vegetable and herb garden. Many symbolic plants were introduced in the courtyard, and it became cultural landscape beyond aesthetic taste. In the vegetable and herb garden, vegetables, fruits and medicinal plants are apparently introduced for epigenetic use. The plants that were displayed to be observed and enjoyed were the sweet flag, pomegranate, daphne odora, chrysanthemum, bamboo, lotus and plum blossom. Seventh, it was possible to understand garden culture related to landscaping materials through poetic words such as pavilions, ponds, stream, flower pot, oddly shaped stones, backyard, orchard, herb garden, flower bed, chrysanthemum fence, boating, fishing, passing the glass around, feet bathing, flower blossom, forest of apricot trees, peach blossoms, stroking the pine tree, plum flower blossoming through the snow and frosted chrysanthemum.

• Journal of Intelligence and Information Systems
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• v.27 no.4
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• pp.73-95
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• 2021

This study uses Node2vec graph embedding method and Light GBM link prediction to explore undeveloped export candidate countries in Korea's food and beverage industry. Node2vec is the method that improves the limit of the structural equivalence representation of the network, which is known to be relatively weak compared to the existing link prediction method based on the number of common neighbors of the network. Therefore, the method is known to show excellent performance in both community detection and structural equivalence of the network. The vector value obtained by embedding the network in this way operates under the condition of a constant length from an arbitrarily designated starting point node. Therefore, it has the advantage that it is easy to apply the sequence of nodes as an input value to the model for downstream tasks such as Logistic Regression, Support Vector Machine, and Random Forest. Based on these features of the Node2vec graph embedding method, this study applied the above method to the international trade information of the Korean food and beverage industry. Through this, we intend to contribute to creating the effect of extensive margin diversification in Korea in the global value chain relationship of the industry. The optimal predictive model derived from the results of this study recorded a precision of 0.95 and a recall of 0.79, and an F1 score of 0.86, showing excellent performance. This performance was shown to be superior to that of the binary classifier based on Logistic Regression set as the baseline model. In the baseline model, a precision of 0.95 and a recall of 0.73 were recorded, and an F1 score of 0.83 was recorded. In addition, the light GBM-based optimal prediction model derived from this study showed superior performance than the link prediction model of previous studies, which is set as a benchmarking model in this study. The predictive model of the previous study recorded only a recall rate of 0.75, but the proposed model of this study showed better performance which recall rate is 0.79. The difference in the performance of the prediction results between benchmarking model and this study model is due to the model learning strategy. In this study, groups were classified by the trade value scale, and prediction models were trained differently for these groups. Specific methods are (1) a method of randomly masking and learning a model for all trades without setting specific conditions for trade value, (2) arbitrarily masking a part of the trades with an average trade value or higher and using the model method, and (3) a method of arbitrarily masking some of the trades with the top 25% or higher trade value and learning the model. As a result of the experiment, it was confirmed that the performance of the model trained by randomly masking some of the trades with the above-average trade value in this method was the best and appeared stably. It was found that most of the results of potential export candidates for Korea derived through the above model appeared appropriate through additional investigation. Combining the above, this study could suggest the practical utility of the link prediction method applying Node2vec and Light GBM. In addition, useful implications could be derived for weight update strategies that can perform better link prediction while training the model. On the other hand, this study also has policy utility because it is applied to trade transactions that have not been performed much in the research related to link prediction based on graph embedding. The results of this study support a rapid response to changes in the global value chain such as the recent US-China trade conflict or Japan's export regulations, and I think that it has sufficient usefulness as a tool for policy decision-making.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.119-133
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• 2011

Sulfonylurea (SU)-resistant weeds include seven annual weeds such as Monochoria vaginalis, Scirpus juncoides and Cyperus difformis, etc., and three perennial weeds of Scirpus planiculmis, Sagittaria pigmaea and Eleocharis acicularis as of 2010 since identification Monochoria korsakowii in the reclaimed rice field in 1998. The Echinochloa oryzoides resistant to acetyl CoA carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors has been confirmed in wet-direct seeding rice field of the southern province, Korea in 2009. In the beginning of occurrence of SU-resistant weeds the M. vaginalis, S. juncoides and C. difformis were rapidly and individually spreaded in different fields, however, theses resistant weeds have been occurring simultaneously in the same filed as time goes by. The resistant biotype by weed species demonstrated about 10- to 1,000-fold resistance, base on $GR_{50}$ (50% growth reduction) values of the SU herbicides tested. And the resistant biotype of E. oryzoides to cyhalofop-butyl, pyriminobac-methyl, and penoxsulam was about 14, 8, and 11 times more resistant than the susceptible biotype base on $GR_{50}$ values. In history of paddy herbicides in Korea, the introduction of SU herbicides including besulfuron-metyl and pyrazosulfuron-ethyl that control many troublesome weeds at low use rates and provide excellent crop safety gave farmers and many workers for herbicide business refreshing jolt. The products and applied area of SU-included herbicides have been rapidly increased, and have accounted for about 69% and 96%, respectively, in Korea. The top ten herbicides by applied area were composed of all SU-included herbicides by 2003. The concentrated and successive treatment of ACCase and ALS inhibitors for control of barnyardgrass in direct-seeded rice led up to the resistance of E. oryzoides. Also, SU-herbicides like pyrazosulfuron-ethyl and imazosulfuron which are effective to barnyardgrass can be bound up with the resistance of E. oryzoides. The ALS activity isolated from the resistant biotype of M. korsakowii to SU-herbicides tested was less sensitive than that of susceptible biotype. The concentration of herbicide required for 50% inhibition of ALS activity ($I_{50}$) of the SU-resistant M. korsakowii was 14- to 76-fold higher as compared to the susceptible biotype. No differences were observed in the rates of [$^{14}C$]bensulfuron uptake and translocation. ALS genes from M. vaginalis resistant and susceptible biotypes against SU-herbicides revealed a single amino acid substitution of proline (CCT), at 197th position based on the M. korsakowii ALS sequence numbering, to serin (TCT) in conserved domain A of the gene. Carfentrazone-ethyl and pyrazolate were used mainly to control SU-resistant M. vaginalis by 2006, the early period, in Korea. However, the alternative herbicides such as benzobicyclone, to be possible to control simultaneously the several resistant weeds, have been developing and using broadly because the several resistant weeds have been occurring simultaneously in the same filed. The top ten herbicides by applied area in Korea have been occupied by products of 3-way mixture type including herbicides with alternative mode of action for the herbicide resistant weeds. Mefenacet, fentrazamide and cafenstrole had excellent controlling effects on the ACCase and ALS inhibitors resistant when they were applied within 2 leaf stage.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.287-302
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• 2017

The carbonate rocks of the Daegi Formation are composed of the limestone at the upper and lower zones, and the dolomite at the middle zone, in which the upper zone has higher CaO content than others. The colors of carbonate rock in the Daegi Formation can be divided into five types; white, light brown, light gray, gray, and dark gray. The white to light gray colored rocks correspond to the high purity limestone with 53.15 ~ 55.64 wt. % CaO, and the light brown colored rocks contain 20.71 ~ 21.67 wt. % MgO. The bleaching of carbonate rocks are not related to CaO composition of the rocks, as light gray rocks tend to be higher in CaO content than those of the white rocks at the lower zone. The pelitic components are also occasionally increased in white limestone than light grey one. $Al_2O_3$ is one of the most difficult content to remove during hydrothermal processes, so the interpretation that the limestone is purified together with hydrothemral bleaching, has little merit. The wide range (over 16 ‰) of ${\delta}^{18}O_{SMOW}$, smaller variation (within 2 ‰) of ${\delta}^{13}C_{PDB}$ are apparent in both the upper and lower zones, which indicate the Daegi Formation had been affected overall by hydrothermal fluids. The K-Ar isotopic age of hydrothermal alteration in the GMI limestone mine is $85.1{\pm}1.7Ma$. Gradual change from grey through light grey to white limestone is accompaned by lower oxygen stable isotope values, which is major evidence that the hydrothermal effect is the main process of the bleaching. Although the Daegi Formation has suffered from hydrothermal activity and increase in whiteness, there is no clear evidence demonstrating the relationship between bleaching and high purity of limestone. The purification of limestone has nothing to do with the hydrothermal activity in this area. Instead, it should be considered that the change of sedimentary environment related to see-level fluctuation which can prevent deposition of pelitic components especially $Al_2O_3$ contrbuted to the formation of the high purity limestone in the upper zone of the Daegi Formation. Considering the evidences such as increase in CaO content of limestone by depth, gradual change from calcite to dolomite at the lower zones, and occurring the high purity limestone at the upper zone, the interpretation of sequence stratigraphic aspect to the formation of the high purity Daegi limestone appears to be more suitable than that of hydrothermal alteration origin.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.343-358
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• 2011

As implant treatment has become popular, lots of different shapes and materials of the implant upper component have been supplied. And there are also diverse reports about failures including loosening of the abutment screw which is one of the most common reason. Purpose : The purpose of this study is to find out how different screw tightening orders and methods influence on screw loosening according to the different connection systems. The upper component was fabricated by casting method. After fabricating master models that are precisely attached to the upper component, 5 experimental models each for the external connection system and internal connection system were fabricated using splinting impression technique. First, to find out the influence of the screw tightening order, screws were tightened in 3 orders; 1-2-3-4, 2-3-1-4, 2-4-3-1. After tightening, removal torque values (RTV) of each group was measured. And also to find out the influence of screw tightening method, a model with 2-3-1-4 screw tightening order was tightened with 30 Ncm at one time(1-step method) and the RTV was compared with the same order group (2-3-1-4) in the 2 step method. In the external connection system, RTV appeared significantly lower in group 2-3-1-4 than group 2-4-3-1 (p<0.05). And also in the internal connection system, the RTV of group 2-3-1-4 appeared significantly lower than that of group 2-4-3-1 and 1-2-3-4 (p<0.05). When comparing the tightening number of the screw without considering the screw tightening order, the first tightened screw appeared significantly higher RTV than the second one in the external connection system (p<0.05), however there was no significant difference from the first tightened screw to the last tightened screw in the internal connection system. And there was no statistically significant difference between the two screw tightening methods in both internal and external connection system. In the comparison of external and internal connection system, each RTV appeared 16.27 Ncm and 14.25 Ncm and appeared as a statistically significant difference (p<0.05). There was a significant difference in RTV measured according to the screw tightening order. The lowest RTV appeared in the groups started tightening from the middle. There was also a significant difference in RTV between the two connection system groups. A further study is needed to find out the influence factors in RTV and also a study is required related to the load condition.