• Title/Summary/Keyword: 수평 유지

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Improving Reliabilities of Dam Displacement based on Monitoring Given Points by Total Station (기준점 측량을 활용한 광파기 기반 댐 제체 변위 계측 신뢰도 향상)

  • Kang, Gi-Chun;Kim, Bong-Jae;Hong, Seok-Woo;Yim, Yeon-Chool;Kim, Ji-Seong
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.1
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    • pp.1-8
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    • 2017
  • Displacement of dams by various instrumentations has been monitored for its safety management and analyzing the behavior after a dam collapse accident. However, unknown displacement of dam has frequently been occurred and it's difficult to analyze behavior of dams more accurately. In this study, improvement of reliabilities for displacement of dams measured by a total station was suggested by calibrating the monitoring system. The position of total station was initially measured through 2-3 given points and the coordinate of the total station was considered as an absolute value. Also, base horizontal and vertical angles had not been considered even if they are important factors when displacement was estimated. In this study, location of the total station and variations of base horizontal and vertical angles were investigated during measuring displacements of targeting points. From the results of this study, they are important factors which are affecting measurements of dam displacements. Before the calibrating, the displacement at 50 m from total station was ±20mm±20mm. After the calibrating, the displacement was decreased by ±5mm±5mm.

Study on The Modification of The Transition Curve to Increase Operating Speed of Existing Line (기존선 속도 향상을 위한 완화곡선 변경 방안 연구)

  • Kim, Jae-Bok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.10
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    • pp.26-32
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    • 2019
  • The purpose of this study is to improve the running speed on a small-radius curved section on an existing train line. When the transition curve was extended, and the amount of movement in the horizontal direction tended to increase as the curve radius increased. The amount of increase in the transition curve extension was lowest when extending the curve radius, and the amount of horizontal movement was the lowest when changing the curve radius to a cosinusoidal curve. As a result of applying the pass rate after improvement to the Kyeongbu line, there was a time-shortening effect of 9.4 to 11.6% and a facial expression speed increasing effect when the curve radius was fixed and the transition curve was changed to a sinusoidal curve. In conclusion, the most effective way to improve the running speed on an existing train route is to change the image to concrete and to change the relaxation curve to a cosinusoidal curve. The amount of horizontal movement of the track is small, and the speed improvement effect is excellent.

An Analysis of the Imported Consumer Goods Distribution Sector of Korea: From a Vertical Structure Viewpoint (수입소비재(輸入消費財) 유통구조(流通構造)의 효율화(效率化) 방안(方案))

  • Nam, Il-chong
    • KDI Journal of Economic Policy
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    • v.13 no.1
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    • pp.3-33
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    • 1991
  • Since the early 1980's, the Korean government has gradually been widening the Korean market to foreign consumer goods. This, combined with the increased purchasing power of the Korean consumers resulting from the continued economic growth of the country, has sparked a spectacular influx of foreign consumer goods into Korea, ranging from BMW's to chopsticks. Import of foreign consumer goods amounted to more than 6 billion dollars in 1989 and is continuing to grow at a rapid rate. The increased import of foreign consumer goods doubtlessly improved the overall welfare of the Korean consumers by providing them with a wider range of options to choose from, by lowering the prices of some of the consumer goods domestically produced, and also by forcing the producers of some Korean goods to face competition with better foreign goods, thus giving them an incentive to raise the quality of their products. However, it is agreed by most economists that this increase in general welfare has been much smaller than what they had expected at the outset. Consumer prices of most imported consumer goods are easily double the import price, and in some cases, more than treble the import prices. Further, there has not been a noticeable drop in the prices of domestically produced consumer goods. Much of the blame has been attributed to the distribution sector of Korea. The objective of this paper is to analyze the imported consumer goods distribution sector of Korea, focusing on the possible sources of the poor performance of that sector, and to make policy suggestions that could potentially increase the welfare. This paper differs from all the previous research by others on this subject in that it analyzes the imported consumer goods distribution sector of Korea as a vertical structure. The distribution sector of an imported consumer good is a vertical structure since it consists of an international market, an import stage, and domestic wholesale and retail markets, in that order vertically. Our study naturally includes the analysis of the vertical restraints as well as the analysis of the industrial organization of each horizontal stage in the vertical structure. Each horizontal component of the imported consumer goods distribution sector is basically a monopolistically competitive market differentiated by characteristics of goods and by the locations and the services of firms. Further, restrictive dealership and resale price maintenance are found to be widely in use. Our main findings are the follwing; First, most consumer goods are imported monopolistically or oligopolistically through restrictive dealership contracts between foreign producers and domestic importers. Such restrictive dealership gives importers market power in the domestic market and explains many of the large discrepancies betwen the consumer prices and the import prices of many goods. Korean anti - trust law does not cover the issues arising from the market power of an importer resulting from a restrictive dealership contract. Second, some major producers of Korean goods are also importers of foreign goods that are substitutes of their products. The import of substitutes by major domestic producers is anti - competitive because it tends to raise the prices of both domestic goods and foreign goods, and also because it reduces the incentive of the domestic producers to raise the quality of their products. Third, wholesalers and retailers widely use resale price maintenance as a price fixing mechanism, and while this is against the anti- trust law, it seldom gets noticed. Fourth, the high level of rents of real estate for commercial use works as an entry barrier to the distribution sector and results in reduced competition by the firms in that sector. Finally, there are information problems. Consumers have inferior information to firms about the quality of a foreign consumer good that they have not tried before. Such information asymmetry often enables firms to raise prices. In addition, information asymmetry between importers frequently delays the import of cheaper substitutes. In order to alleviate the problems indentified above, we suggest the following policy changes. The government should strengthen the anti - trust law and its enforcement to regulate restrictive import contracts, import of competing goods by major domestic producers, and RPM by wholesalers and retailers that is aimed at price fixing. In addition, the government should loosen its tight real estate policy to encourage investment in the distribution sector. Finally, we suggest that the import price revelation policy that has been in use for some items since 1990 be expanded to most imported consumer goods that are introduced for the first time to give consumer better information and be used only for the period of time needed to inform sufficient number of consumers.

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Ship Collision Risk Analysis of Bridge Piers (선박충돌로 인한 교각의 위험도 분석)

  • Lee, Seong-Lo;Bae, Yong-Gwi
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.4
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    • pp.169-176
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    • 2005
  • An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions.

Experimental Study on Structural Behavior of Double Ribbed Deep-Deck Plate under Construction Loads (시공하중이 작용하는 더블리브 깊은 데크플레이트의 구조거동에 대한 실험적 연구)

  • Heo, Inwook;Han, Sun-Jin;Choi, Seung-Ho;Kim, Kang Su;Kim, Sung-Bae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.7
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    • pp.49-57
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    • 2019
  • Recently, the use of deep deck plate has been increased in various structures, such as underground parking lots, logistics warehouses, because it can reduce construction periods and labor costs. In this study, a newly developed Double Deck (D-deck) plate which can leads to save story heights has been introduced, and experimental tests on a total of five D-deck plates under construction loads have been carried out to investigate their structural performance at construction stage. The loads were applied by sands and concrete to simulate the actual distributed loading conditions, and the vertical deflection of D-Deck and the horizontal deformation of web were measured and analyzed in detail. As a result, it was confirmed that all the D-decks showed very small vertical deflection of less than 5.34 mm under construction loads, which satisfies the maximum deflection limit of L / 180. In addition, the D-Deck plate was found to have a sufficient rigidity to resist construction loads in a stable manner.

Comparative observations of lingualized occlusion and monoplane occlusion in the treatment of severe atrophy of edentulous mandible (심한 하악 치조골 흡수를 보이는 환자에서 설측 교두 교합과 단일평면 교합을 비교 관찰한 의치 수복 증례)

  • Ahn, Gyo-zin;Lee, Joon-Seok
    • Journal of Dental Rehabilitation and Applied Science
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    • v.34 no.2
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    • pp.127-136
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    • 2018
  • The patient who has severely absorbed residual ridges, treatments are challenging to satisfy many factors: support, retention, stability, etc. The neutral zone or monoplane occlusion with non-anatomical tooth would be helpful to get additional retention and stability. The monoplane occlusion has been used long time because it can eliminate horizontal forces and many other advantages. The lingualized occlusion was introduced to improve chewing efficiency and esthetics. But from a stability aspect, it seems controversy between monoplane occlusion and lingualized occlusion. This case report shows the results of the treat two flat residual ridge patients using functional impression; piezography, and made 2 other dentures with monoplane and lingualized occlusion that patient can select denture.

Consolidation Model and Numerical Analysis for Soft Clay Ground Considering Characteristics of Material Function (물질함수특성을 고려한 연약 점토지반의 압밀모델 및 수치해석)

  • Jeon, Je-Sung;Yi, Chang-Tok;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.123-136
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    • 2004
  • Terzaghi's one-dimensional consolidation theory has some important assumption, which can't be applicable to predict the behavior of soft clay ground. Especially, predictions using infinitesimal strain and linear material function related with permeability can give rise to mistake in comparison with the result of real behavior in site. For this reason, Gibson et al. established a rigorous formulation for the one-dimensional nonlinear finite strain consolidation theory, which can consider non-linearity of material function. But it is difficult to apply this theory to predict the behavior of common soft clay ground with vertical drain. In this study, consolidation model which can consider the vertical and horizontal flow of a fully saturated clay layer, self-weight of soil and nonlinear characteristics of compressibility and permeability are derived. Numerical analysis scheme, which can be applied to consolidation analysis by derived consolidation model in this study was developed. The characteristics of material function were examined using laboratory testing such as standard consolidation test, Rowe-cell test and modified consolidation test.

Hybrid Element Model for Wave Transformation Analysis (파랑 변형 해석을 위한 복합 요소 모형)

  • 정태화;박우선;서경덕
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.15 no.3
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    • pp.159-166
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    • 2003
  • In this study, we develop a finite element model to directly solve the Laplace equation while keeping the same computational efficiency as the models based on the extended mild-slope equation which has been widely used for calculation of wave transformation in shallow water. For this, the computational domain is discretized into finite elements with a single layer in the vertical direction. The velocity potential in the element is then expressed in terms of the potentials at the nodes located at water surface, and the Galerkin method is used to construct the numerical model. A common shape function is adopted in horizontal direction, and the cosine hyperbolic function in vertical direction, which describes the vertical behavior of progressive waves. The model was developed for vertical two-dimensional problems. In order to verify the developed model, it is applied to vertical two-dimensional problems of wave reflection and transmission. It is shown that the present finite element model is comparable to the models based on extended mild-slope equations in both computational efficiency and accuracy.

Real Time Balancing Control of 2 Wheel Robot Using a Predictive Controller (예측 제어기를 이용한 2바퀴 로봇의 실시간 균형제어)

  • Kang, Jin-Gu
    • Journal of the Korea Society of Computer and Information
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    • v.19 no.3
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    • pp.11-16
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    • 2014
  • In this paper, the two-wheels robot using a predictive controller to maintain the balance of the posture control in real time have been examined. A reaction wheel pendulum control method is adopted to maintain the balance while the bicycle robot is driving. The objective of this research was to design and implement a self-balancing algorithm using the dsPIC30F4013 embedded processor. To calculate the attitude in ARS using 2 axis gyro(roll, pitch) and 3 axis accelerometers (x, y, z). In this study, the disturbance of the posture for the asymmetrical propose to overcome the predictive controller which was a problem in the control of a remote system by introducing the two wheels of the robot controller and the linear prediction of the system controller combines the simulation was performed. Also, the robust characteristic for realizing the goal of designing a loop filter too robust controller is designed so that satisfactory stability of the control system to improve stability of the system to minimize degradation of performance was confirmed.

Mechanical Loads of Dropper for High Speed Electric Railway (고속 전차선로 드로퍼에 대한 기계적 하중에 관한 연구)

  • Lee, Gi-Chun;Lee, Tae-Hoon;Lee, Jong-Woo
    • Journal of the Korean Society for Railway
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    • v.14 no.3
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    • pp.222-227
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    • 2011
  • The dropper supports the contact wire and is attached using various types of dropper clips on the catenary. Droppers are subject to mechanical stress from buckling during the passage of pantographs. In order to investigate failure causes for the high speed line dropper, theoretical analyses and experiments have been carried out. In this paper, mathematical formulas are derived for the pre-sag of the dropper static load. The measured values in the experiment were similar to the theoretical predictions. To analyze the cause on fracture of dropper wire, we have conducted analysis such as SEM(Scanning Electron Microscope) of fractured specimens in the field and new specimens. Finally, we performed measurement for the variation of dynamic load on the dropper when a pantograph moved at 300km/h under the Korean high speed overhead line. If such mechanical load occur repeatedly with every passing pantograph, it is possible that the dropper wire will break due to fatigue. This results will be used for special management of high speed catenary system maintenance and life estimation of dropper.