• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.419-429
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• 2003

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of thick, hyperboloidal shells of revolution. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sub r/, u/sub θ/, u/sub z/ in the radial, circumferential, and axial directions, respectively, we taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the r and z directions. Potential(strain) and kinetic energies of the hyperboloidal shells are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the hyperboloidal shells of revolution. Numerical results are tabulated for eighteen configurations of completely free hyperboloidal shells of revolution having two different shell thickness ratios, three variant axis ratios, and three types of shell height ratios. Poisson's ratio (ν) is fixed at 0.3. Comparisons we made among the frequencies for these hyperboloidal shells and ones which ate cylindrical or nearly cylindrical( small meridional curvature. ) The method is applicable to thin hyperboloidal shells, as well as thick and very thick ones.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.953-959
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• 2018

This paper deals with controlling surge oscillations of a mooring vessel system under large external disturbances such as wind, waves and currents. A control synthesis based on Sliding Mode Control (SMC) with a Super-Twisting Algorithm (STA) has been applied to suppress nonlinear surge oscillations of a two-point mooring system. Despite the advantages of robustness against parameter uncertainties and disturbances for SMC, chattering is the main drawback for implementing sliding mode controllers. First-order SMC shows convergence within the desired level of accuracy, in which chattering is the main obstacle related to the destructive phenomenon. Alternatively, STA completely eliminates chattering phenomenon with high accuracy even for large disturbances. SMC based on STA is an effective tool for the motion control of a nonlinear mooring system because it avoids the chattering problems of a first-order sliding mode controller. In addition, the error trajectories of controlled mooring systems implemented by means of STA form in the bounded region. Finally, the control gain effect of STA can be observed in sliding surface and position trajectory errors.

• Korean journal of applied entomology
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• v.16 no.3 s.32
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• pp.171-179
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• 1977

Since the outbreak of the brown planthopper (Nilaparvata lugens) in 1915 caused tremendous losses in rice production, one of the more effective method of prevention of such a disaster could be the establishment of longterm forecasting system, In 1916 the author indicated there was a correlation between sunspot activities and brown planthopper and the white back planthopper outbreaks. However, the examples seem to be too small size to state a definite correlation. The purpose of the present study IS to revi~w the history of the brown planthopper outbreaks, and to establish a more effective forcasting system. The present forcasting methods are based on light trap catches of adults which already migrate into this country from mainland China. The regular cycle of 11.2 years of sunspot activity began in 1710, and was continued to present. To gather more records of brown planthopper, the author checked 'Joseon Wangjo Silrok' and analized the so-called 'Hwang' 'Hwang-chung' and 'Chung' which have multiple meanings, together with 'Samguk Sagi' 'Goryo Sa' and 'Munheon Bigo.' The results obtained by the about from review of these old literature citations revealed that ten species of insect and unknown species were involved: i. e., pine moth (Dendrolimus spectabilis), army worm (Mythimna separata), brown planthopper (Nilarvata lugens), white-back planthopper (Sogatella furcifera), migratory locust (Locutsa migratoria), rice stem borer (Chilo suppressalis,), mole cricket (Gryllotalpa africana), rice-plant weevil (Echinocnemus squameus), cut worm (Euxoa segetum), and mulberry pyralid Margaronia pyloalis) The suspected incidence of planthopper in old records expressed by 'Hwang' or 'Chung' revealed a total or 25 out of 37 in 'Samguk sagi,' 21 out of 49 in 'Goryo sa,' 9 of 73 in 'Wanjo-silrog,' and none of 8 in 'Munheon bigo' were planthoppers. Therefore, a total of 36 out of 167 records of insect incidence in the old literature can be possibly attributed to planthoppers. The brown planthopper and white-back planthopper migrate together to Korea every year from mainland China, However, the number of each species are differ by year. In 1975 outbreak the brown planthopper was dominant; and the white-back planthopper prevailed in 1946 and 1977 outbreaks, During the course of this study, the author was able to add a new record of outbreak of planthop per. In 1916 the white-back planthopper outbreak caused serious losses in Chungcheong-namdo and Jeonla-namdo, with losses estimated as high as 160 and 190 thousand seok (23.2 and 27.5 thousand M/T), in Naju and Secheon county, respectively. Since 1912, major outbreaks of brown planthopper or white-back planthopper have been recored 5 times. These occurrences coincide and well matched the period of minimum number of sunspots, With these authenticated records of planthoppers, the author believes there is a close correlation between brown planthopper and white-back planthopper outbreaks in Korea and sunspot activities. Therefore, in years of low number of sunspots, we should watch for and expect outbreaks of these. insects. At this time, it will be necessary to provide all possible prevention measures.

• Journal of Science of Art and Design
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• v.11
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• pp.201-220
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• 2007

From two viewpoints the writer investigated the beauty of space by overall arrangement and composition of a picture in Oriental painting. In particular, she examined the expanded representation and significance of space use which had not properly been recognized in the field of a colored picture contrary to a painting in India ink. She studied that the boundary for the representation and appreciation of space was unlimited to one field of painting by studying and analyzing it in connection with other fields of art which had something in common with it in techniques or languages of representation. The writer considered the aspects of similar forms and spirits as the methods of understanding and representing the essence of an object in creating a work. She generally considered the aspect of perfecting knowledge by studying the principle of an actual thing for the representation of revealed forms corresponding to the aspect of similar forms, and tried to reach the stage of 'materialization' united with the spirit of the subject of creation for the formless forms corresponding to the aspect of representing an artist's inner world as well as the external shapes of things. She tried to reach the stage of spiritual cultivation in pursuit of the boundary between 'mental vanity' and 'sitting quietly and attaining the state of perfect selflessness', which were presented by Chuang-tzu, to express the spirituality internal to it. She recognized that the projection of the cultivation on a work could convey internal essence as well as external forms to a picture. It was because the image of the form represented in a picture was based on the aesthetic experience got from realty. In the concept of space and a method of representing it, she explored and analyzed the basic concept of space, arranged the concept of space shown in Oriental ideas dividing it into the concepts of space in Confucianism, Taoism and the Zen sect. What she felt acutely through this study was that she should establish the identity of her work by succeeding to, changing and re-creating tradition based on the historical heritage left by successive excellent painters and theorists. Putting together all these things showed that establishing the identity in the world of work pursued and oriented by her required searching the direction in future works by mixing tradition with modern times in a creative way, which is just the purpose of study in this thesis.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.72-92
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• 2023

As described above, the location of Jagiso eunchon in Goheung-hyeon and the nature of Undae-ri kiln site were examined. Goheung-hyeon's administrative agency was moved to Joyang-hyeon, which is now Joseong-myeon, Boseong-gun in 1395. Therefore, Goheung-hyeon Jagiso Eunchon in Sejongsillok Jiriji corresponding to 1424~1432 should be found in the west of Joseong-myeon, Boseong, where the administrative agency was moved in 1395. Among the four boundaries of Goheung-hyeon recorded in the 『Sejongsillok』 Jiriji, it is recorded as 2-ri by the sea in the south and 8-ri by Nakan in the east. If the current Goheung-hyeon is Goheung-hyeon's administrative agency in the Sejongsillok Jiriji Records Compilation Period, it cannot be the boundary the south and east mentioned above. This is because it cannot be 2-ri from the current Goheung-eup to the sea in the south, and Nakan is close to the north, not the east, as recorded. However, it has already been suggested that Joyanghyeonseong(朝陽縣城), located in Gonae Village, Ucheon-ri, Josung-myeon, Boseonggun is an Goheunghyeon's administrative agency. And if the four-way boundary of Goheung-hyeon was converted into the current distance unit based on this place(Joyanghyeonseong, 朝陽縣城), an approximate result could be obtained even if it did not exactly match. Therefore, it is highly likely that Goheung-hyeon's administrative agency, which was moved to Joyang-hyeon, Boseong in 1395, is Gonae Village, Ucheon-ri, JoSeong-myeon, Boseong. Jagiso eunchon(犾村) in Goheung-hyeon can be interpreted as a "dog-shouting village." It is thought to be a meaning structure of "animal + sound". A place name thought to have the same structure was identified in Jeongheung-ri, west of Ucheon-ri, Joseongmyeon, Boseong. It is the name of a village called Hoeum-dong(虎吟洞), and it is interpreted as the sound of a tiger or the bark of a tiger, which is the same as the meaning structure of Eunchon. However, there is Gaesan Village in the south of Hoeum-dong, and a Buncheong ware kiln site was identified around it. At this kiln site, a fragment of carved Buncheong ware engraved with the character "Eon", which corresponds to the right stroke of the character "Seom (贍)" in the name "Naeseom (內贍)" was identified. A small amount of Buncheong ware and Joseon celadon pieces were also identified. It can be seen that the Buncheong ware paid to the government was made by checking the Buncheong ware with the government name engraved on it. On the west side of Joyanghyeonseong Fortress in Ucheon-ri, joseong-myeon, Boseong, which was the administrative agency of Goheung-hyeon and the area around the Gaesan Buncheong ware kiln site in Jeongheung-ri, where the Buncheong ware paid to the government was, is thought to be Jagiso Eunchon, Goheung-hyeon. Jagiso and Dogiso are located in the four directions based on the administrative agency. Naturally, the location of Jagiso and Dogiso is also determined on where the administrative agency of Hyeon is. Since the Goheung-hyeon's administrative agency in the early Joseon Dynasty was moved to Ucheon-ri, joseong-myeon, Boseong-myeon, it is necessary to naturally find Jagiso and Dogiso in Boseong. In addition, regarding the nature of the kiln site in Undae-ri, the aspects of the excavated relics were considered. As a result, it is believed that the Undae-ri kiln site functioned as a jagiso in Heungyang-hyeon from February 1441 to the 1470s. If so, the "Ye" Buncheong ware, which was collected around Undae-ri kiln No. 7, could be naturally understood.

• Journal of Korean Society of Transportation
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• v.20 no.2
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• pp.105-115
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• 2002

For many rears, traffic accident statistics are the most direct measure of safety for a signalized intersection. However it takes more than 2 or 3 yearn to collect certain accident data for adequate sample sizes. And the accident data itself is unreliable because of the difference between accident data recorded and accident that is actually occurred. Therefore, it is rather difficult to evaluate safety for a intersection by using accident data. For these reasons, traffic conflict technique(TCT) was developed as a buick and accurate counter-measure of safety for a intersection. However, the collected conflict data is not always reliable because there is absence of clear criteria for conflict. This study developed objective and accurate conflict criteria, which is shown below based on traffic engineering theory. Frist, the rear-end conflict is regarded, when the following vehicle takes evasive maneuver against the first vehicle within a certain distance, according to car-following theory. Second, lane-change conflict is regarded when the following vehicle takes evasive maneuver against first vehicle which is changing its lane within the minimum stopping distance of the following vehicle. Third, cross and opposing-left turn conflicts are regarded when the vehicle which receives green sign takes evasive maneuver against the vehicle which lost its right-of-way crossing a intersection. As a result of correlation analysis between conflict and accident, it is verified that the suggested conflict criteria in this study ave applicable. And it is proven that estimating safety evaluation for a intersection with conflict data is possible, according to the regression analysis preformed between accident and conflict, EPDO accident and conflict. Adopting the conflict criteria suggested in this study would be both quick and accurate method for diagnosing safety and operational deficiencies and for evaluation improvements at intersections. Further research is required to refine the suggested conflict criteria to extend its application. In addition, it is necessary to develope other types of conflict criteria, not included in this study, in later study.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.47-60
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• 2010

Most of the researches about classification usually have used kNN(k-Nearest Neighbor), SVM(Support Vector Machine), which are known as learn-based model, and Bayesian classifier, NNA(Neural Network Algorithm), which are known as statistics-based methods. However, there are some limitations of space and time when classifying so many web pages in recent internet. Moreover, most studies of classification are using uni-gram feature representation which is not good to represent real meaning of words. In case of Korean web page classification, there are some problems because of korean words property that the words have multiple meanings(polysemy). For these reasons, LSA(Latent Semantic Analysis) is proposed to classify well in these environment(large data set and words' polysemy). LSA uses SVD(Singular Value Decomposition) which decomposes the original term-document matrix to three different matrices and reduces their dimension. From this SVD's work, it is possible to create new low-level semantic space for representing vectors, which can make classification efficient and analyze latent meaning of words or document(or web pages). Although LSA is good at classification, it has some drawbacks in classification. As SVD reduces dimensions of matrix and creates new semantic space, it doesn't consider which dimensions discriminate vectors well but it does consider which dimensions represent vectors well. It is a reason why LSA doesn't improve performance of classification as expectation. In this paper, we propose new LSA which selects optimal dimensions to discriminate and represent vectors well as minimizing drawbacks and improving performance. This method that we propose shows better and more stable performance than other LSAs' in low-dimension space. In addition, we derive more improvement in classification as creating and selecting features by reducing stopwords and weighting specific values to them statistically.

• KDI Journal of Economic Policy
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• v.12 no.2
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• pp.51-79
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• 1990

Research on technical efficiency, an important dimension of market performance, had received little attention until recently by most industrial organization empiricists, the reason being that traditional microeconomic theory simply assumed away any form of inefficiency in production. Recently, however, an increasing number of research efforts have been conducted to answer questions such as: To what extent do technical ineffciencies exist in the production activities of firms and plants? What are the factors accounting for the level of inefficiency found and those explaining the interindustry difference in technical inefficiency? Are there any significant international differences in the levels of technical efficiency and, if so, how can we reconcile these results with the observed pattern of international trade, etc? As the first in a series of studies on the technical efficiency of Korea's manufacturing industries, this paper attempts to answer some of these questions. Since the estimation of technical efficiency requires the use of plant-level data for each of the five-digit KSIC industries available from the Census of Manufactures, one may consture the findings of this paper as empirical evidence of technical efficiency in Korea's manufacturing industries at the most disaggregated level. We start by clarifying the relationship among the various concepts of efficiency-allocative effciency, factor-price efficiency, technical efficiency, Leibenstein's X-efficiency, and scale efficiency. It then becomes clear that unless certain ceteris paribus assumptions are satisfied, our estimates of technical inefficiency are in fact related to factor price inefficiency as well. The empirical model employed is, what is called, a stochastic frontier production function which divides the stochastic term into two different components-one with a symmetric distribution for pure white noise and the other for technical inefficiency with an asymmetric distribution. A translog production function is assumed for the functional relationship between inputs and output, and was estimated by the corrected ordinary least squares method. The second and third sample moments of the regression residuals are then used to yield estimates of four different types of measures for technical (in) efficiency. The entire range of manufacturing industries can be divided into two groups, depending on whether or not the distribution of estimated regression residuals allows a successful estimation of technical efficiency. The regression equation employing value added as the dependent variable gives a greater number of "successful" industries than the one using gross output. The correlation among estimates of the different measures of efficiency appears to be high, while the estimates of efficiency based on different regression equations seem almost uncorrelated. Thus, in the subsequent analysis of the determinants of interindustry variations in technical efficiency, the choice of the regression equation in the previous stage will affect the outcome significantly.

• Women's Studies Review
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• v.27 no.1
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• pp.3-36
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• 2010

This paper is based on the certain point that 'the indigenous', which have long been occupied by the Asian patriarchy or the local communities, now calls for the repositioning in the feminist context. 'The indigenous', in one part, generally refer to the matured long-standing traditions and practices of certain regional, or local communities, as a mode of a place specific way of endowing the world with integral meaning. In the narrow definition, it points to the particular form of placed based knowledge for survival, for example, the useful knowledge of a population who have lived experiences of the environment. In the other part, 'the indigenous' could be criticized in the gender perspectives because it has been served as an ideological tool for patriarchy and sexism, which have undermined women's body and subjectivity in the name of the Asian traditional community. That's why the feminists with sensitivity to the discourses of it, may perceive it very differently, still hesitating dealing with the problem. However, even if there are tendencies that the conservatives romanticize local traditions and essentialize 'the indigenous', as it were, it does not exist 'out there'. Then, it could be scrutinized in the contemporary context which, especially, needs to seek the possibility towards the alternatively post - develope mental knowledge system. In the face of global economic crisis which might be resulted from the instrumentalized or fragmented knowledge production system, it's holistic conceptions that human, society, and nature should not be isolated from each other. is able to give an insightful thinking. It will work in the restraint condition that we reconceptualize the indigenous knowledge not as an unchanging artefact of a timeless culture, but as a dynamic, living and culturally meaningful system towards the ecofeminstic indigenous knowledge. And then, indigenous renaissance phenomena which empower non-western culture and knowledge system and generate increased consciousness of cultural membership. Thus, this paper argues that the indigenous knowledges which have been underestimated in the western-centered knowledge-power relations, could be reconstructed as a potential resources of ecological civility transnationally which reconnect individuals and societies with nature.