• Title/Summary/Keyword: Constraints condition

Search Result 383, Processing Time 0.035 seconds

Automatic Extraction of Buildings using Aerial Photo and Airborne LIDAR Data (항공사진과 항공레이저 데이터를 이용한 건물 자동추출)

  • 조우석;이영진;좌윤석
    • Korean Journal of Remote Sensing
    • /
    • v.19 no.4
    • /
    • pp.307-317
    • /
    • 2003
  • This paper presents an algorithm that automatically extracts buildings among many different features on the earth surface by fusing LIDAR data with panchromatic aerial images. The proposed algorithm consists of three stages such as point level process, polygon level process, parameter space level process. At the first stage, we eliminate gross errors and apply a local maxima filter to detect building candidate points from the raw laser scanning data. After then, a grouping procedure is performed for segmenting raw LIDAR data and the segmented LIDAR data is polygonized by the encasing polygon algorithm developed in the research. At the second stage, we eliminate non-building polygons using several constraints such as area and circularity. At the last stage, all the polygons generated at the second stage are projected onto the aerial stereo images through collinearity condition equations. Finally, we fuse the projected encasing polygons with edges detected by image processing for refining the building segments. The experimental results showed that the RMSEs of building corners in X, Y and Z were 8.1cm, 24.7cm, 35.9cm, respectively.

Capacity Design of Eccentrically Braced Frame Using Multiobjective Optimization Technique (다목적 최적화 기법을 이용한 편심가새골조의 역량설계)

  • Hong, Yun-Su;Yu, Eunjong
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.33 no.6
    • /
    • pp.419-426
    • /
    • 2020
  • The structural design of the steel eccentrically braced frame (EBF) was developed and analyzed in this study through multiobjective optimization (MOO). For the optimal design, NSGA-II which is one of the genetic algorithms was utilized. The amount of structure and interfloor displacement were selected as the objective functions of the MOO. The constraints include strength ratio and rotation angle of the link, which are required by structural standards and have forms of the penalty function such that the values of the objective functions increase drastically when a condition is violated. The regulations in the code provision for the EBF system are based on the concept of capacity design, that is, only the link members are allowed to yield, whereas the remaining members are intended to withstand the member forces within their elastic ranges. However, although the pareto front obtained from MOO satisfies the regulations in the code provision, the actual nonlinear behavior shows that the plastic deformation is concentrated in the link member of a certain story, resulting in the formation of a soft story, which violates the capacity design concept in the design code. To address this problem, another constraint based on the Eurocode was added to ensure that the maximum values of the shear overstrength factors of all links did not exceed 1.25 times the minimum values. When this constraint was added, it was observed that the resulting pareto front complied with both the design regulations and capacity design concept. Ratios of the link length to beam span ranged from 10% to 14%, which was within the category of shear links. The overall design is dominated by the constraint on the link's overstrength factor ratio. Design characteristics required by the design code, such as interstory drift and member strength ratios, were conservatively compared to the allowable values.

Transformation of Flight Load to Test Load for the Static Load Test of External Fuel Tank for Aircraft (항공기용 외부연료탱크 정하중시험을 위한 비행하중의 시험하중으로의 변환)

  • Kim, Hyun-gi;Kim, Sung Chan;Park, Sung Hwan;Ha, Byoung Geun;An, Su Hong;Kim, Jun Tae
    • Journal of Aerospace System Engineering
    • /
    • v.15 no.1
    • /
    • pp.80-85
    • /
    • 2021
  • In this study, for conducting a static load test of an external fuel tank used for an aircraft, the flight load acting on the external fuel tank was converted to the test load and the suitability of the converted test loads was confirmed. In order to calculate the test load from the flight load, the external fuel tank was divided into several sections. Shear load, moment by unit shear load, and unit moment were calculated for each section. Test loads for each section were then calculated by computing the shear load, the moment of each section, and flight load condition. In actual static load tests, it might not be possible to impose the test load in the calculated position due to physical constraints. Therefore, after determining positions in which the load could be imposed in the actual test, the test load calculated for each section was redistributed to selected positions. Finally, a test load plan was established by applying a whiffle tree to enhance the efficiency of the test performance while making it easier to operate the actuator. The reliability of the test load plan was verified by comparing it with flight load conditions.

Improvement in Rice Cultural Techniques Against Unfavorable Weather Condition (기상재해와 수도재배상의 대책)

  • Ryu, I.S.;Lee, J.H.;Kwon, Y.W.
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.27 no.4
    • /
    • pp.385-397
    • /
    • 1982
  • The climatic impacts have been the environmental constraints with soil characteristics to achieve self sufficiency of food production in Korea. In this paper, the distribution and appearance of impacts and the changes in climatological status due to recent trend of early transplanting of rice are widely discussed to derive some countermeasures against the impacts, being focussed on cultural A long term analysis of the climatic impact appearances of the last 74 years showed that drought, strong wind, flood, cold spell and frost were the major impacts. Before 1970's, the drought damage was the greatest among the climatic impacts; however, the expansion and improvement of irrigation and drainage system markedly decreased the damage of drought and heavy rain. The appearance of cold damage became more frequent than before due to introduction of early transplanting for more thermophilic new varieties. Tongillines which were from Indica and Japonica crosses throw more attention to cold damage for high yields to secure high temperature in heading and ripening stages and lead weakness to cold and drought damage in early growth stage after transplanting. The plants became subject to heavy rain in ripening stage also. For the countermeasures against cold damage, the rational distribution of adequate varieties according to the regional climatic conditions and planting schedule should be imposed on the cultivation. A detoured water way to increase water temperature might be suggestable in the early growth stage. Heavy application of phosphate to boost rooting and tillering also would be a nutritional control method. In the heading and ripening stages, foliar application of phosphate and additional fertilization of silicate might be considerable way of nutritional control. Since the amount of solar radiation and air temperature in dry years were high, healthy plants for high yield could be obtained; therefere, the expansion of irrigation system and development of subsurface water should be performed as one of the national development projects. To minimize the damage of strong wind and rainfall, the rational distribution of varieties with different growing periods in the area where the damage occurred habitualy should be considered with installation of wind breaks. Not only vertical windbreaks but also a horizontal wind break using a net might be a possible way to decrease the white heads in rice field by dry wind. Finally, to establish the integrated countermeasures against the climatic impacts, the detailed interpretation on the regional climatic conditions should be conducted to understand distribution and frequency of the impacts. The expansion of observation net work for agricultural meteorology and development of analysis techniques for meteorological data must be conducted in future together with the development of the new cultural techniques.

  • PDF

Dynamic Limit and Predatory Pricing Under Uncertainty (불확실성하(不確實性下)의 동태적(動態的) 진입제한(進入制限) 및 약탈가격(掠奪價格) 책정(策定))

  • Yoo, Yoon-ha
    • KDI Journal of Economic Policy
    • /
    • v.13 no.1
    • /
    • pp.151-166
    • /
    • 1991
  • In this paper, a simple game-theoretic entry deterrence model is developed that integrates both limit pricing and predatory pricing. While there have been extensive studies which have dealt with predation and limit pricing separately, no study so far has analyzed these closely related practices in a unified framework. Treating each practice as if it were an independent phenomenon is, of course, an analytical necessity to abstract from complex realities. However, welfare analysis based on such a model may give misleading policy implications. By analyzing limit and predatory pricing within a single framework, this paper attempts to shed some light on the effects of interactions between these two frequently cited tactics of entry deterrence. Another distinctive feature of the paper is that limit and predatory pricing emerge, in equilibrium, as rational, profit maximizing strategies in the model. Until recently, the only conclusion from formal analyses of predatory pricing was that predation is unlikely to take place if every economic agent is assumed to be rational. This conclusion rests upon the argument that predation is costly; that is, it inflicts more losses upon the predator than upon the rival producer, and, therefore, is unlikely to succeed in driving out the rival, who understands that the price cutting, if it ever takes place, must be temporary. Recently several attempts have been made to overcome this modelling difficulty by Kreps and Wilson, Milgram and Roberts, Benoit, Fudenberg and Tirole, and Roberts. With the exception of Roberts, however, these studies, though successful in preserving the rationality of players, still share one serious weakness in that they resort to ad hoc, external constraints in order to generate profit maximizing predation. The present paper uses a highly stylized model of Cournot duopoly and derives the equilibrium predatory strategy without invoking external constraints except the assumption of asymmetrically distributed information. The underlying intuition behind the model can be summarized as follows. Imagine a firm that is considering entry into a monopolist's market but is uncertain about the incumbent firm's cost structure. If the monopolist has low cost, the rival would rather not enter because it would be difficult to compete with an efficient, low-cost firm. If the monopolist has high costs, however, the rival will definitely enter the market because it can make positive profits. In this situation, if the incumbent firm unwittingly produces its monopoly output, the entrant can infer the nature of the monopolist's cost by observing the monopolist's price. Knowing this, the high cost monopolist increases its output level up to what would have been produced by a low cost firm in an effort to conceal its cost condition. This constitutes limit pricing. The same logic applies when there is a rival competitor in the market. Producing a high cost duopoly output is self-revealing and thus to be avoided. Therefore, the firm chooses to produce the low cost duopoly output, consequently inflicting losses to the entrant or rival producer, thus acting in a predatory manner. The policy implications of the analysis are rather mixed. Contrary to the widely accepted hypothesis that predation is, at best, a negative sum game, and thus, a strategy that is unlikely to be played from the outset, this paper concludes that predation can be real occurence by showing that it can arise as an effective profit maximizing strategy. This conclusion alone may imply that the government can play a role in increasing the consumer welfare, say, by banning predation or limit pricing. However, the problem is that it is rather difficult to ascribe any welfare losses to these kinds of entry deterring practices. This difficulty arises from the fact that if the same practices have been adopted by a low cost firm, they could not be called entry-deterring. Moreover, the high cost incumbent in the model is doing exactly what the low cost firm would have done to keep the market to itself. All in all, this paper suggests that a government injunction of limit and predatory pricing should be applied with great care, evaluating each case on its own basis. Hasty generalization may work to the detriment, rather than the enhancement of consumer welfare.

  • PDF

An Empirical Testing of Employee Attchment Model: A Comprison of South Korean and U.S. Teachers (조직유착모형의 경험적 적합성에 관한 고찰 - 교사들의 경우를 중심으로 한 한 . 미간 비교연구 -)

  • 조동기
    • Korea journal of population studies
    • /
    • v.19 no.1
    • /
    • pp.139-159
    • /
    • 1996
  • This study comparatively examines a causal model of employee attatchment which focuses on employee's organizational commitment and intent to stay with an organization. This study is based on two separate studies of employee attachment among teachers : the U.S. case of the Chicago Public Schools (CPS) and the South Korean case of the Seoul Educational District (SED). The main purpose of this study is to replicate in Korea the CPS study. A revised model based on the unique characteristics of Korean teachers is also developed and estimated. The Price Mueller model of employee attachment provides the basic theoretical framework for this study. It includes five general classes of variables : 1) employee responses to work variables : job satisfaction, commitment, and intent to stay; 2) psychological stress variables: role ambiguity, role conflict, work overload, and quality of students; 3) social structural variables: autonomy, routinization, distributive justice, and legitimacy; 4) economic structural variables: pay, job security, promotional opportunities, and job opportunities; and 5) work orientation variables : career commitment, normative commitment, work motivation, affectivity, work values, and met expectations. The data was collected through questionnaire survey and a sample of 649 secondary school teachers in Seoul, South Korea, was included in the final analysis. Covariance structure analysis (LISREL) was used to estimate the causal model. The results indicate that the endogenous variables of job satisfaction and commitment play a considerably less important role than in the U.S. model in mediating the effects of the exogenous variables on intent to stay, and the model fails to explain the majority of the variance in intent to stay. In addition, the new variables added to the revised Korean model do not bave significant effects on intent to stay. The structural characteristics of the employment relationship and labor markets associated with Korean teachers forced mobility and closed external markets - are largely accountable for the major differences between the Korean and the U.S. cases. The study suggests that conceptual and empirical work on what produces employee attachment under these structural constraints needs to receive more attention in future studies.

  • PDF

A Decade of Comparative Study on the Changes in Elementary and Secondary School Science Teachers' Professionalism and Perceptions of Integrated Science Education (초·중등 과학교사들의 통합과학교육에 대한 인식과 교사 전문성에 관한 10년 주기(2008-2018) 비교 연구)

  • Maeng, Hee-Ju;Son, Yeon-A
    • Journal of The Korean Association For Science Education
    • /
    • v.39 no.6
    • /
    • pp.717-728
    • /
    • 2019
  • The cultivation of creative convergence talent has become more important than ever, the Korean curriculum has also undergone many changes, aiming for convergence and integrated education. In addition to these changes in science and curriculum, we examined the changes in perception and Professionalism(PCK) of integrated science education of science teachers over the past decade. For this study, 359 elementary and secondary science teachers in 2008, when the 2007 revised curriculum was applied, and 360 elementary and secondary science teachers in 2018, when the 2015 revised curriculum was applied, were examined for 10 years of changes in perceptions and PCK of integrated science education. The conclusions from the analysis were as follows. First, in 2018, elementary and secondary science teachers were found to have a statistically significant increase in awareness of integrated science education. Nevertheless, cognition was found to be 'normal'. Second, teachers' perception of the necessity of improving the professionalism of teachers, providing teaching and learning materials, reducing the contents of learning, reducing the number of students and securing flexible timetables, and raising the perception of integrated science education for students and parents as a condition for the success of integrated science education, was analyzed to be significantly higher in 2018. Third, the results of PCK survey through self-diagnosis, teachers' PCK on integrated science education, such as competence to secure curriculum contents knowledge, comprehension of curriculum and class composition related to integrated science education, teaching strategy for integrated, creation of teaching and learning environment for integrated teaching, efforts to improve administrative constraints and the professionalism of integrated science education, was significantly higher than it was ten years ago. Therefore, the recent emphasis on convergence education has increased the experience of applying convergence classes in the field of education, and it was seen as a result of the continuous efforts of science teachers to meet the changes in the education paradigm.

Optimization of the Truss Structures Using Member Stress Approximate method (응력근사해법(應力近似解法)을 이용한 평면(平面)트러스구조물(構造物)의 형상최적화(形狀最適化)에 관한 연구(研究))

  • Lee, Gyu Won;You, Hee Jung
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.13 no.2
    • /
    • pp.73-84
    • /
    • 1993
  • In this research, configuration design optimization of plane truss structure has been tested by using decomposition technique. In the first level, the problem of transferring the nonlinear programming problem to linear programming problem has been effectively solved and the number of the structural analysis necessary for doing the sensitivity analysis can be decreased by developing stress constraint into member stress approximation according to the design space approach which has been proved to be efficient to the sensitivity analysis. And the weight function has been adopted as cost function in order to minimize structures. For the design constraint, allowable stress, buckling stress, displacement constraint under multi-condition and upper and lower constraints of the design variable are considered. In the second level, the nodal point coordinates of the truss structure are used as coordinating variable and the objective function has been taken as the weight function. By treating the nodal point coordinates as design variable, unconstrained optimal design problems are easy to solve. The decomposition method which optimize the section areas in the first level and optimize configuration variables in the second level was applied to the plane truss structures. The numerical comparisons with results which are obtained from numerical test for several truss structures with various shapes and any design criteria show that convergence rate is very fast regardless of constraint types and configuration of truss structures. And the optimal configuration of the truss structures obtained in this study is almost the identical one from other results. The total weight couldbe decreased by 5.4% - 15.4% when optimal configuration was accomplished, though there is some difference.

  • PDF

A Study on Martial art for suggesting the role of Martial art Sports as a Leisure Activity (여가활동으로서의 무도스포츠 역할 재고를 위한 고찰)

  • Lim, Young-Sam
    • Journal of the Korean Applied Science and Technology
    • /
    • v.37 no.3
    • /
    • pp.564-570
    • /
    • 2020
  • The purpose of this study is to examine the preceding studies and suggest alternatives to establish the role and value of martial arts sports as a leisure activity. To achieve the purpose of this study, the keywords and themes of leisure-related journals were extracted and the articles and current status of martial arts-related journals in Korea were derived using SPSS descriptive statistics method. The subjects of the analysis were 'mudo' and 'leisure' of leisure-related journals between 2005 and 2017, and an interpretative textual analysis was conducted to analyze the contents of individual studies. According to the results of the survey on the actual condition of participation in the 2016 National Sports for all, Taekwondo was ranked 5th among the top 5 sports with 6.1% of the sports for all, and Taekwondo and Kendo were ranked 1st and 2nd respectively in the sports for all students and the clubs that they want to join in the future. Second, the study on martial arts in the journals related to leisure was found most in 2006 and 2010, but only one study was not conducted after 2014, which confirmed that the absolute number of studies was very insufficient. Third, the research themes of the journals related to leisure were serious leisure, female college students, physical self-concept, social development, leisure recreation class, job satisfaction, life satisfaction, training, leisure constraints, etc., and the study of martial arts related to leisure was found to require quantitative and qualitative multilateral approaches. Fourth, in the current status of dance related studies by year in domestic journals, two of 23 studies in 2007 were conducted on leisure topics, and the average number of studies related to domestic martial arts and leisure related papers was 5.65%, which is very low. In conclusion, as a result of analyzing the trend of research on leisure as a martial arts sport, it is necessary to suggest the direction of future research that can reconsider the role and value of martial arts sport as a leisure activity that can improve the quality of life and happiness in future society through quantitative and qualitative improvement.

An Analysis of the Managerial Level's Gender Gap and "Glass Ceiling" of the Corporation (기업 관리직의 젠더 격차와 "유리천장" 분석)

  • Cho, Heawon;Hahm, Inhee
    • 한국사회정책
    • /
    • v.23 no.2
    • /
    • pp.49-81
    • /
    • 2016
  • This study agrees with the idea that a situation centered perspective provides a useful contribution in understanding women's attitude on organizations. Women's occupational experiences are less related to their "femaleness" than to the structural constraints inherent in the occupational positions women fill. So characteristics of the organizational situation including gender composition and hierarchical status may "shape and define" women's experience on the job. The present study examined the managerial level's gender gap and "glass ceiling" of the corporation. According to Kanter, if the ratio of women to men in organizations begins to shift, as affirmative action and new hiring and promotion policies promised, forms of relationships and corporate culture should also change. However, the mere presence of women on workplace may not, in itself, result in women-friendly work condition. This study analyzes "Korean Women Manger Panel survey(2010 3rd. wave)" to examine how much gender gap of the managerial level persists and when the glass ceiling effect emerges. Using t-test and ANOVA, various aspects of the gender gap within managerial level were verified. The most significant finding is the glass ceiling effect starts from very low level of management. Policy implications from the statistical analysis of the Panel survey are: 1) We need to increase the absolute number of the women managers for securing middle level women leadership pipe line. 2) We need to confront the fact that the glass ceiling starts from the very low managerial level, and to explore more realistic way to break up the vicious circle for the tokenism. and 3) We need to looking beyond numbers in approaching women's matter at work. At the cultural and institutional level, work-family programs and policies, women's ratings of their competence, and family-friendly organization's climate should be considered.