• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.4
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• pp.243-248
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• 2022

Weight optimization was performed for a rotorcraft shaft system using one-dimensional Euler-Bernoulli beam elements. Torsion, shaft support stiffness such as bearings, flange mass are all considered. To guarantee structural dynamic stability, eigenvalue analysis was performed to avoid critical speed and tooth mesh excitation form the gearbox. The weight optimization was performed by adjusting the thickness and radius while the length of the shaft was fixed, and the optimization process was divided into two stages. In the first, the weight is optimized with the torsional strength constraint. In the second, the difference between the primary mode of shaft and the critical speed is maximized so that the primary mode of the shaft can avoid the critical speed while the constraint on the torsional strength of the shaft is satisfied according to the standard for shaft system stability (AMC P 706-201, 1974). The proposed method was verified by comparing the results of the optimal design using the given one-dimensional beam elements with the stress results of the 3D finite element and the actual manufactured shaft.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.57-64
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• 2007

This study proposes a method to estimate drilling torque during ground boring with an aid of electrical energy required for rotating a boring-auger. Ground boring is commonly used in geotechnical engineering such as preboring precast pile installation, soil-cement grouting, ground exploration and so forth. In order to understand the correlation between required electrical energy to rotate the boring auger and the drilling torque, a small laboratory apparatus was designed and a pilot study was performed. The apparatus rotates common drill bits of $D=5{\sim}25mm$ in CBR specimens. The velocity of a bit is 19 RPM and predefined using a reduction gear which connects a main rotation axis to a 25 Watts AC electrical motor shaft. In the middle of drilling the motor current increments and the drilling torque were measured and the correlation between the current and the torque was obtained through linear square fits. Based on the correlation the acquired motor current during drilling was applied to predict the drilling torque in consequent testing and the prediction results were compared to the measured torque. The comparison leads a conclusion that the motor current during drilling using electrical power may be a good indicator to estimate/determine strength characteristics of the ground.

• Journal of Intelligence and Information Systems
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• v.22 no.3
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• pp.165-183
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• 2016

Over the past decade, there has been a rapid diffusion of technological devices and a rising number of various devices, resulting in an escalation of virtual reality technology. Technological market has rapidly been changed from smartphone to wearable devices based on virtual reality. Virtual reality can make users feel real situation through sensing interaction, voice, motion capture and so on. Facebook.com, Google, Samsung, LG, Sony and so on have investigated developing platform of virtual reality. the pricing of virtual reality devices also had decreased into 30% from their launched period. Thus market infrastructure in virtual reality have rapidly been developed to crease marketplace. However, most consumers recognize that virtual reality is not ease to purchase or use. That could not lead consumers to positive attitude for devices and purchase the related devices in the early market. Through previous studies related to virtual reality, there are few studies focusing on why the devices for virtual reality stayed in early stage in adoption & diffusion context in the market. Almost previous studies considered the reasons of hard adoption for innovative products in the viewpoints of Typology of Innovation Resistance, MIR(Management of Innovation Resistant), UTAUT & UTAUT2. However, product-based antecedents also important to increase user intention to purchase and use products in the technological market. In this study, we focus on user acceptance and resistance for increasing purchase and usage promotions of wearable devices related to virtual reality based on headgear products like Galaxy Gear. Especially, we added a variables like attitude confidence as a dimension for user resistance. The research questions of this study are follows. First, how attitude confidence and innovativeness resistance affect user intention to use? Second, What factors related to content and brand contexts can affect user intention to use? This research collected data from the participants who have experiences using virtual rality headgears aged between 20s to 50s located in South Korea. In order to collect data, this study used a pilot test and through making face-to-face interviews on three specialists, face validity and content validity were evaluated for the questionnaire validity. Cleansing the data, we dropped some outliers and data of irrelevant papers. Totally, 156 responses were used for testing the suggested hypotheses. Through collecting data, demographics and the relationships among variables were analyzed through conducting structural equation modeling by PLS. The data showed that the sex of respondents who have experience using social commerce sites (male=86(55.1%), female=70(44.9%). The ages of respondents are mostly from 20s (74.4%) to 30s (16.7%). 126 respondents (80.8%) have used virtual reality devices. The results of our model estimation are as follows. With the exception of Hypothesis 1 and 7, which deals with the two relationships between brand awareness to attitude confidence, and quality of content to perceived enjoyment, all of our hypotheses were supported. In compliance with our hypotheses, perceived ease of use (H2) and use innovativeness (H3) were supported with its positively influence for the attitude confidence. This finding indicates that the more ease of use and innovativeness for devices increased, the more users' attitude confidence increased. Perceived price (H4), enjoyment (H5), Quantity of contents (H6) significantly increase user resistance. However, perceived price positively affect user innovativeness resistance meanwhile perceived enjoyment and quantity of contents negatively affect user innovativeness resistance. In addition, aesthetic exterior (H6) was also positively associated with perceived price (p<0.01). Also projection quality (H8) can increase perceived enjoyment (p<0.05). Finally, attitude confidence (H10) increased user intention to use virtual reality devices. however user resistance (H11) negatively affect user intention to use virtual reality devices. The findings of this study show that attitude confidence and user innovativeness resistance differently influence customer intention for using virtual reality devices. There are two distinct characteristic of attitude confidence: perceived ease of use and user innovativeness. This study identified the antecedents of different roles of perceived price (aesthetic exterior) and perceived enjoyment (quality of contents & projection quality). The findings indicated that brand awareness and quality of contents for virtual reality is not formed within virtual reality market yet. Therefore, firms should developed brand awareness for their product in the virtual market to increase market share.

• Journal of the Daesoon Academy of Sciences
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• v.36
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• pp.1-34
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• 2020

It has been suggested that Jeungsan's prophetic poem that starts with the verse "For about seven or eight years, there will be a castle in the ancient country [七八年間古國城] ⋯" originally comes from Prophecies of Jeong Gam (鄭鑑錄). Despite Jeungsan, himself, obviously having been critical of that text, this claim has become the basic grounds for discourse suggesting that Jeungsan was not only interested in Prophecies of Jeong Gam but also considerably influenced by the text. However, the claim itself was formulated due to misunderstandings of the Chinese poems that had been included in A Compilation of Secret Prophecies Hidden in the Family-clan of Seogye (西溪家臧訣). These poems pursue a different ideological orientation than the poem from Prophecies of Jeong Gam. Ultimately, the Chinese poem in the verse 84 the chapter titled, Prophetic Elucidations in The Canonical Scripture of Daesoon Jinrihoe cannot provide a basis for the claim that Jeungsan was strongly influenced by Prophecies of Jeong Gam. This claim that Prophecies of Jeong Gam made a deep impact on Jeungsan and Daesoon Thought was based on three other texts outside of those that appear within verse 84 of Prophetic Elucidations. The first supposedly-related line is: "Heaven opens at the period of the Rat (Ja 子), Earth opens at the period of the Ox (Chuk 丑), humankind starts at the period of the Tiger (Ihn 寅)." This line comes from from Shao Kangjie's Book of Supreme World Ordering Principles (皇極經世), and the line could be quoted idiomatically as an expression in the Joseon Dynasty. Accordingly, attempts to relate Daesoon Thought to Prophecies of Jeong Gam are a distortion that arise from the assumption that Jeungsan had a significant interest in Prophecies of Jeong Gam. The second related line is "At the foot of Mount Mother (母岳山), a golden icon of Buddha has the ability to speak [母岳山下 金佛能言]." That line is nearly identical to the verse "On the summit of Mount Mother, a golden icon of Buddha has the ability to speak [母岳山頭 金佛能言]." Yet, Jeungsan changed '頭 (du, the summit)' to '下 (ha, the foot or under)' and express his own unique religious prophecy. This allusion to the prophecies of Jeong Gam is actually a criticism designed to disprove the earlier prophecy. Third, is the verse, "The form of Buddhism, creation of daoism, and propriety of Confucianism [佛之形體仙之造化儒之凡節]," which is characteristically related to Daesoon Thought. This verse can only be found in the prophetic text, Prophecies of Chochang (蕉蒼訣), and it is provided a main source when alleging that Prophecies of Jeong Gam was an influence on Daesoon Thought. However, considering the context of Prophecies of Chochang and the year of its publication (it is assumed to be compiled after 1950s), this does not hold water as Jeungsan had already passed into Heaven several decades before that time. This disqualifies the verse from being a basis for asserting Prophecies of Jeong Gam as an influence on Daesoon Thought. Contrary to the original assertion, there is a considerable amount of evidence that Prophecies of Chochang absorbed aspects of Daesoon Thought, which were simply revised in a novel way. There is no truly compelling evidence underpinning the argument that Prophecies of Jeong Gam had a unilateral impact on Daesoon Thought. There seems to be a great deal of confusion and numerous misinterpretations on this matter. Therefore, the claim that Daesoon Thought, as developed by Jeungsan, was influenced by the discourse on dynastic revolution and feng shui contained in Prophecies of Jeong Gam should be re-examined at the level of its very premise.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.563-580
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• 1998

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal on masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal on masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth displacement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch wire, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased 3. When MDAW and Class II elastics were applied, the teeth movement were sir flu with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.

• Analytical Science and Technology
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• v.27 no.1
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• pp.41-59
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• 2014

The aims of this work were the identification and the classification of fresh lubricants and used engine oils of vehicles for the application in forensic science field-80 kinds of fresh lubricants were purchased and 86 kinds of used engine oils were sampled from 24 kinds of diesel and gasoline vehicles with different driving conditions. The sample of lubricants and used engine oils were analyzed by GC/MS. The Bayesian model technique was developed for classification or identification. Both the wavelet fitting and the principal component analysis (PCA) techniques as a data dimension reduction were applied. In fresh lubricants classification, the rates of matching by Bayesian model technique with wavelet fitting and PCA were 97.5% and 96.7%, respectively. The Bayesian model technique with wavelet fitting was better to classify lubricants than it with PCA based on dimension reduction. And we selected the Bayesian model technique with wavelet fitting for classification of lubricants. The other experiment was the analysis of used engine oils which were collected from vehicles with the several mileage up to 5,000 km after replacing engine oil. The eighty six kinds of used engine oil sample with the mileage were collected. In vehicle classification (total 24 classes), the rate of matching by Bayesian model with wavelet fitting was 86.4%. However, in the vehicle's fuel type classification (whether it is gasoline vehicle or diesel vehicle, only total 2 classes), the rate of matching was 99.6%. In the used engine oil brands classification (total 6 classes), the rate of matching was 97.3%.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.664-671
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• 2019

This study was conducted to investigate the environmental impact of the construction of the Yeongju Dam, located near the upper stream of the Nakdong River, on benthic macroinvertebrates. The investigation was conducted four times from 2015 to 2016 and the composition of the benthic macroinvertebrate fauna from the four surveyed sites was compared. After the dam construction, the number of benthic macroinvertebrate species decreased and the species composition ratio of the E.P.T taxa(Ephemeroptera, Plecoptera, and Trichoptera) decreased, which favored the previous environment and the large riverbed structure. However, the species composition ratio of the O.C.H taxa (Odonata, Coleoptera, and Hemiptera), which favored the reservoir environment, increased. For the pattern of changes in the functional habitat groups, the proportion of 'Clinger(CL)' taxa decreased and the 'Burrower(BU), Climber(CB), Sprawler(SP), Swimmer(SW)' taxa increased in all surveys after the dam construction. A cluster stability comparison showed that the 'Stability Group II' species of St.2 and St.3 showed a drastic decrease. The average Benthic Macroinvertebrate Index(BMI) of all the survey sites in 2016 was lower than that in 2015. This research confirmed the temporal and spatial changes in the habitat type and community structure of the benthic macroinvertebrates resulting from the dam construction.

• (The) Research of the performance art and culture
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• no.39
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• pp.801-833
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• 2019

This article has reviewed on the characteristics of the Beompae (Buddhist chanting) performed by Gyeongjaeeosan Wonmyeongchang(唱) based on the result of musical style of Gyeongjae Anchaebi-sori as defined under the previous studies. And, through the comparison with the Beompae performed by Songam-chang (唱), a same type of musical piece, it contemplates on musical differences between the two singers. Results of the study are shown as follows. of Gyeongjaeeosan Seolhoeinyu-pyeon and of Socheongsaja-pyeon are sunged as Yuchi-Seong(聲) among Anchaebi-sori. 'main melody type' and 'ending type' are generally similar to the musical characteristics of the Yuchi-Seong(聲), and the differences between the two singers are detected from main melody type D and ending type b. In particular, under of Socheongsaja-pyeon, only the type a is detected among the two types. becouse ending note of ending-type 'a' is ended with 'sol'. The basic frame of the Jjaimsae(musical form) has been clarified in the previous studies that the Jjaimsae of Yuchi-Seong(聲) has been maintained just the way it is. However, even for the same Seong(聲), the combination of the 'main melody type' of passage has not been unified, and depending on the musical piece, it has been discovered that the combination of the 'main melody type' has been diversely organized. of Gyeongjaeeosan Bongsongsajapyeon belongs to Pyeon-gae-seong(聲) broadly from the Anchaebi-sori and it is shown to be So-seong(聲) in details. In particular, in the previous studies, the 'ending melody' of So-seong(聲) and the closing melody of were similar with a slight difference for the 'ending melody'. Such a difference is relation to the characteristics for sequentially descending melody of Wonmyeong-chang(唱). The 'Jjaimsae(The musical structure)' is not much different from the previous studies, and the 'yeok-eum(weaving lyrics)' of Songam-chang(唱) has strong tendency of 3-sobak rhythm while the Wonmyeong-chang (唱) is shown the tendency of 2-sobak rhythm in general for the difference.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.148-156
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• 2022

Ecological occupation in irrigation ponds is a well-acknowledged fact that is essential for biodiversity conservation in agricultural ecosystems. However, there are few studies on the ecological functions and relationship between a paddy field and irrigation using macroinvertebrates in an environmentally friendly paddy field. The objective of this study is to identify the community and distribution characteristics of macroinvertebrates in an agricultural paddy field and irrigation pond ecosystems, and to provide basic data on the ecological function of an environmentally friendly paddy field. Macroinvertebrate sampling was conducted from May to September in an agricultural paddy field and irrigation pond in an environment-friendly paddy field in Boryeong city. We conducted a study to identify the distribution characteristics using macroinvertebrate species analysis, such as Functional Feeding Groups (FFGs), Habitat Oriented Groups (HOGs), rarefaction curve, and a two-way dendrogram. A total of 37 species of macroinvertebrates in 28 families, 13 orders were collected study during the period of the investigation. Dominant taxa of macroinvertebrates included Coleoptera, Hemiptera, and Odonata. In terms of FFGs, predators and gathering collectors accounted for approximately 70%, in relation to HOGs, and climbers and swimmers occupied more than 50% from both the paddy field and irrigation pond. With respect to the rarefaction curve, the irrigation pond (July) was high as E (S, 141)=18 species, while the paddy field (May) was comparatively low as E (S, 141)=9 species. In conclusion, our results revealed that macroinvertebrates, such as Notonecta triguttata, Peltodytes intermedius, Appasus major, Laccotrephes japonensis, Appasus japonicus, Sigara substriata, Enochrus simulans, and Sternolophus rufipes, were used as a habitat and spawning ground in both paddy field and irrigation pond. The irrigation pond appears to be a very important spawning ground for macroinvertebrates.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.46-57
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• 2014

This study analyzes whether the value-added structure of Korean wind power industry exhibits a virtuous cycle through the value chain(VC) within wind power firms and the value system(VS) among the wind power industries, using a regression analysis based on a survey about Korean wind power companies. According to the VC, the government's R&D support is analyzed to have contributed to an increase in the R&D investments of the wind power companies. An increase in corporates' R&D investments has led to an increase in corporates' R&D outputs, and in turn, induced a remarkable increase in the amounts of production. But an increase in production has not led to a decrease in the costs of production, not resulting in an increase in profit rates per sales amount. In addition, while an increase in profit rates is analyzed to have contributed to an increase in production, this did not induce further investments in corporate's R&D. The virtuous cycle of the value chain in Korean wind power firms is, therefore, analyzed to be weak. Next, the VS is analyzed by dividing the whole chain into the system group including rotor blades, gear boxes, and power generators, and the structure group, such as towers. Two groups are analyzed to have mutually positive effects in the processes of the government's support for corporates' R&D, corporates' investment in R&D, R&D outputs, and profit rates per sales amount. Such mutual positive effects are, however, not found in the processes of the amounts of production and the costs of production. These results demonstrates that the value system of Korean wind power industry is not completed. This study has a policy implication to need further efforts to create the virtuous cycle in the VC and VS of Korean wind power industry.