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Bearing Strength of Steel Baseplate under Eccentric Loads (편심축력(偏心軸力)을 받는 철골구조(鐵骨構造) 주각부(柱脚部)의 지압강도(支壓强度))

  • Choi, Mun Sik;Min, Byung Yeol
    • Journal of Korean Society of Steel Construction
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    • v.15 no.6 s.67
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    • pp.683-691
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    • 2003
  • Recently, the steel has been increaseingly used as an integrated part of high-rise buildings, which often composed of steel structures, steel reinforced concrete structures and composite structures. The steel base is designed to transfer the stresses induced from steel column to the reinforced concrete footing through the base plate. However, in the design of steel structures and steel reinforced concrete structure, it is generally difficult to evaluate the bearing strength of the steel base subjected to large axial force. Furthermore, the material used in steel base is quite different from those used in other connections and a load transferring mechanism of steel base is very complicated in nature. Therefore, a special attention must be placed in design and construction of steel base. In generally, the bearing strength test and research of the steel base subjected to concentrated load are carried out. But, in the design of the structures, uniaxial eccentric load is loaded to the steel base of the steel structures. In this research, the bearing strength and the me of failure considering eccentric loads and eccentric length, were experimented when eccentric load is loaded to the steel base of steel structures. Based on the test results, a basic design reference is suggested for a reasonable design of steel structures, steel reinforced concrete structures and composite structures.

A Study on the Factors Retarding the Development of Public Libraries in Korea - With a Special Reference to the Consciousness of Librarians & Users- (한국의 전통문화와 공동도서관에 관한 연구)

  • Park In-Ung
    • Journal of the Korean Society for Library and Information Science
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    • v.16
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    • pp.207-242
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    • 1989
  • This study hypothesizes that the present deadlock situation in public library development in Korea has chiefly been caused by the underdevelopment of the consciousness of the librarians themselves presently employed in various levels of public libraries throughout the country. This study, therefore, aims to define the areas in librarians' consciousness in which elements of backwardness prevail, and thereby to produce a theoretical framework to develop public library services in Korea on an indigenous footing. To do this, the present author set up a relationship between the traditional consciousness of the Korean People and the public library performances, based on existing published materials. In order to prove hisirelatonship, he then sent out questionnaires to public librarians and male high school students and analyzed the answered questionnaires using Pearson's Correlation Analysis and Multiple Regression Analysis. Results of the analysis are asfollows: 1) Those who place an importance on the show of respectability tend to prefer to work in an indirect services area. 2) Male librarians tend to show a job satisfaction because of chances of promotion reflecting a positive correlation between this-worldiness of librarians and their job satisfaction. 3) Male librarians tend to be satisfied in their job for the conviction for their self-accomplishment, and female librarians tend to be satisfied in their job for the attention and respect they receive from users. 4) Library technicians tend to draw their job satisfaction from their sense of job stability. 5) Male librarians tend to be dissatisfied for the lack of the monetary rewards they receive, while female librarians tend to be dissatisfied for the lack of promotional chances. 6) Most librarians tend to maintain a positive job attitude for the promotional chances, reflecting a positive correlation between this­worldliness in librarians and their service attitude. 7) Power-orientednes in librarians and their job satisfaction correlate negatively in the case of male librarians. This does not apply to female librarians. 8) Power-orientedness and good service attitude correlate negatively in the case of male librarians. This does not apply to female librarians. 9) The fact that male high school students desire to enter good colleges and universities and to obtain a position in his job positively correlate to the fact that public libraries have transformed themselves into a mere reading room. 10) Male library science students show a maladjustment in their major department in earlier years for the professional uncertainty, and as they advance into senior years they show a positive attitude about the library profession.

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Cause Analysis and Improvement Suggestion for Flood Accident in Dorimcheon - Focused on the Tripping and Isolation Accidents (도림천에서 발생한 고립 및 실족사고의 원인분석을 통한 개선방안 도출에 관한 연구)

  • Lee, Kyung-Su;Jeon, Jong-Hyeong;Kim, Tai-Hoon;Kim, Hyunju
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.4
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    • pp.25-36
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    • 2021
  • This study analyzed the causes of flood accidents, such as isolation and lost footing accidents in Dorimcheon, to provide legal and institutional improvements. For cause analysis, Field Investigation, Stakeholder Interview, Report, manual, Law et al. Review, Analysis of water level change characteristics, automatic alarm issuance standard level analysis, and evacuation time according to river control were evaluated. Dorimcheon has the characteristics of a typical urban river, which is disadvantageous in terms of water control. In addition, the risk of flood accidents is high because the section where fatal accidents occur forms sharply curved channels. Tripping and isolation accidents occur in the floodplain watch and evacuation stage, which is the stage before the flood watch and warning is issued. Because floodplain evacuation is issued only when the water level rises to the floodplain, an immediate response according to the rainfall forecast is essential. Furthermore, considering that the rate of water level rise is up to 2.62 cm/min in Sillimgyo 3 and Gwanakdorimgyo, sufficient evacuation time is not secured after the floodplain watch is issued. Considering that fatal accidents occurred 0.46 m below the standard water level for the flood watch, complete control is very important, such as blocking the entry of rivers to prevent accidents. Based on these results, four improvement measures were suggested, and it is expected to contribute to the prevention of Tripping and Isolation Accidents occurring in rivers.

Centrifuge Model Tests on Trafficability of Very Soft Ground Treated with Geotextile and Sand Mat (토목섬유와 모래로 처리된 초연약지반의 장비주행성에 대한 원심모형실험)

  • Jun, Sang-Hyun;Lee, Jong-Ho;Yoo, Nam-Jae
    • Journal of the Korean Geotechnical Society
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    • v.26 no.3
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    • pp.13-23
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    • 2010
  • In this study, centrifuge model tests with 50 g gravitational condition were performed to evaluate the bearing capacity of very soft ground, improved by spreading geotextile and sand on the surface of ground, for the heavy machinery to be able to access. For undrained shear strength of ground model, prepared with the clay sampled from the field, being in the range of 3.1~11.7 kPa, bearing capacity tests were performed with the model footing and the loading system built to simulate the heavy machinery on the ground model treated with geotextile and sand. Test results were compared with theoretically and numerically evaluated ones. Test results about load-settlement curves showed that the bearing capacity increases with the increase of the undrained shear strength of ground. Punching shear or local shear failure was also observed. For a relatively low undrained shear strength of ground, settlement behavior is found to be crucial to evaluating the trafficability of machinery whereas bearing capacity becomes a dominant factor with the increase of undrained shear strength of ground. The method for assessing the bearing capacity of the ground related to trafficability of machinery is presented by acquiring the regression relationship between the contact pressure of machinery and settlements using load-settlement curves with the change of the undrained shear strength. Furthermore, results of numerical analyses about load-settlement relation are in relatively good agreement with those of centrifuge model test.

A Constitutive Model for Rotation of Principal Stress Axes during Direct Simple Shear Deformation (직접단순전단변형에 따른 주응력 방향의 회전을 고려한 구성모델)

  • Park, Sung-Sik;Lee, Jong-Cheon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.53-62
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    • 2008
  • A constitutive model, which can simulate the effect of principal stress rotation associated with direct simple shear test, is proposed in this study. The model is based on two mobilized planes. The plastic strains occur from the two mobilized planes, and depend on stress state, and they are added. The first plane is a plane of maximum shear stress, which rotates about the horizontal axis, and the second plane is a horizontal plane which is spatially fixed. The second plane is used to consider the effect of principal stress rotation on simple shear tests under different stress states. The soil skeleton behavior observed in drained simple shear tests is captured in the model. This constitutive model is incorporated into the dynamic coupled stress-flow finite difference program FLAC. The model is first calibrated with drained simple shear tests on loose Fraser River sand. The measured shear stress and volume change are partially induced by principal stress rotation and compared with model calculations. The model is verified by comparing predicted and measured settlements due to rigid footing resting on loose sands. Settlements predicted by the proposed model were very similar to measured settlements. Mohr-Coulomb model can not consider the effect of principal stress rotation and its prediction was only 20% of measured settlements.

A Knowledge-based Approach for the Estimation of Effective Sampling Station Frequencies in Benthic Ecological Assessments (지식기반적 방법을 활용한 저서생태계 평가의 유효 조사정점 개수 산정)

  • Yoo, Jae-Won;Kim, Chang-Soo;Jung, Hoe-In;Lee, Yong-Woo;Lee, Man-Woo;Lee, Chang-Gun;Jin, Sung-Ju;Maeng, Jun-Ho;Hong, Jae-Sang
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.16 no.3
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    • pp.147-154
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    • 2011
  • Decision making in Environmental Impact Assessment (EIA) and Consultation on the Coastal Area Utilization (CCAU) is footing on the survey reports, thus requires concrete and accurate information on the natural habitats. In spite of the importance of reporting the ecological quality and status of habitats, the accumulated knowledge and recent techniques in ecology such as the use of investigated cases and indicators/indices have not been utilized in evaluation processes. Even the EIA report does not contain sufficient information required in a decision making process for conservation and development. In addition, for CCAU, sampling efforts were so limited that only two or a few stations were set in most study cases. This hampers transferring key ecological information to both specialist review and decision making processes. Hence, setting the effective number of sampling stations can be said as a prior step for better assessment. We introduced a few statistical techniques to determine the number of sampling stations in macrobenthos surveys. However, the application of the techniques requires a preliminary study that cannot be performed under the current assessment frame. An analysis of the spatial configuration of sampling stations from 19 previous studies was carried out as an alternative approach, based on the assumption that those configurations reported in scientific journal contribute to successful understanding of the ecological phenomena. The distance between stations and number of sampling stations in a $4{\times}4$ km unit area were calculated, and the medians of each parameter were 2.3 km, and 3, respectively. For each study, approximated survey area (ASA, $km^2$) was obtained by using the number of sampling stations in a unit area (NSSU) and total number of sampling stations (TNSS). To predict either appropriate ASA or NSSU/TNSS, we found and suggested statistically significant functional relationship among ASA, survey purpose and NSSU. This empirical approach will contribute to increasing sampling effort in a field survey and communicating with reasonable data and information in EIA and CCAU.

Comparison of Construction Costs for Bridge Foundation with Optimization of Steel and PHC Embedded Piles (강관 및 PHC 매입말뚝의 최적화에 따른 교량기초의 공사비 비교)

  • Yun, Jung-Mann;Yea, Geu-Guwen;Kim, Hong-Yeon;Kim, Dong-Min;Kim, Soo-Lo
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.4
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    • pp.71-78
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    • 2016
  • In this study, execution costs of the foundation system are compared with PHC and steel pile in the same soil layers and load condition. Steel piles installed on the thin weathered rock are reduced as 12.5% in comparison with the number of PHC piles. Steel piles installed on the soft rock through weathered rock with 1.7m of thickness reduce the number of piles as 35.7% (STK 400) and 46.4% (STK 490), respectively, in comparison with PHC piles installed on the weathered rock. Also, they reduce the number of piles as 26.5% (STK 400) and 38.8% (STK 490), respectively, in comparison with steel piles (STK 400) installed on the weathered rock. When the thickness of footings is constant, steel piles installed on the soft rock may reduce the area of footings up to 12.2% (STK 400) and 45.4% (STK 490), respectively, in comparison with PHC piles installed on the weathered rock. Total cost of foundation system installed on the soft rock with steel piles (STK 400) increases as 12%, whereas in case of replaced with steel piles (STK 490), it reduces as 16% in comparison with PHC piles installed on the weathered rock. This is because the cost reduction due to the number of piles and footing area is more effective despite high cost of steel piles (STK 490). When the thickness of weathered rock is less than 5m, installing steel piles (STK 490) on the soft rock through it is more economic in comparison with installing PHC piles on the weathered rock.

An Experimental Study on Optimum Slanting Angle in Reticulated Root Piles Installation (그물식 뿌리말뚝의 최적 타설경사각에 관한 실험 연구)

  • 이승현;김병일
    • Geotechnical Engineering
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    • v.11 no.2
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    • pp.29-36
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    • 1995
  • Load testis are executed on model reticulated root piles (RRP) to figure out the optimum slanting angle in the piles installation. One set of model RRP consists of 8 slanting piles which are installed in circular patterns forming two concentric circles, each of which is made by 4 piles. Each pile which is a steel bar of 5m in diameter and 300mm in length is coated to become a pile of 6.5mm in diameter. The slanting angle of the model RRP varies from 0$^{\circ}$ to 20$^{\circ}$ Comparing ultimate bearing capacities of the model RRP of different installation angles, it is observed that the ultimate capacities of the RRP increase as the installation angle increases until 15$^{\circ}$, and the optimum slanting angle of the RRP is around 15$^{\circ}$ The ultimate bearing capacity of the 15$^{\circ}$-RRP is found to be 22% bigger than that of the vertical RRP and 120% bigger than that of the circular surface footing whose diameter is same with the circle formed by outer root piles'heads. However, it is noticed that when the slanting angle of the RRP is increased over 15$^{\circ}$, the ultimate capacity starts to be reduced. The ultimate capacity of 20$^{\circ}$-RRP is even smaller than that of the vertical RRP by as much as 5%. From the observation of the load settlement curve obtained during the RRP load tests, it is known that as the slanting angle gets bigger the load -settlement behavior becomes more ductile.

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The Main Contents, Comment and Future Task for the Space Laws in Korea (한국에 있어 우주법의 주요내용, 논평과 장래의 과제)

  • Kim, Doo-Hwan
    • The Korean Journal of Air & Space Law and Policy
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    • v.24 no.1
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    • pp.119-152
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    • 2009
  • Korea now has a rapidly expanding and developing space programme with exploration aspirations. The government is giving priority to the aerospace industry and, to put it on a better footing, enacted an Aerospace Industry Development Promotion Act in I987, a Space Development Promotion Act in 2005 and a Space Compensation for Damage Act in 2007. I would like to describe briefly the legislative history, main contents and comment for these three space acts including especially launch licensing, registration of space objects, use of satellite information, astronaut rescue, liability for compensation, third party liability insurance and establishment of committee and plans to assist the Korean space effort. Furthermore author proposed to legislate a new draft for the establishment of a Korean Aerospace Development Agency (KADA: tentative title) to create a similar body to Japan Aerospace Exploration Agency (JAXA), British National Space Centre (BNSC) of UK, French Centre National d'Etudes Spatiales (CNES), German Aerospace Center (DLR), Swedish Space Corporation (SSC), China Aerospace Science and Industry Corporation (CASIC), Indian Space Research Organization (ISRO) as well as the Korean Space Agency (KSA: Tentative title) to create a similar body to Canadian Space Agency, European Space Agency, Russian Space Agency, Italian Space Agency, Israel Space Agency, Indian Department of Space, National Aeronautics and Space Administration (NASA) of USA, China National Space Administration in order to develope efficiently space industry. If the Korean government will be establish the Korean Space Agency as an governmental organization in future, it is necessary to revise the contents of the Government Organization Act. It is desirable and necessary for us to establish an Asian Space Agency (ASA), in order to develop our space industry and to promote research cooperation among Asian countries, based on oriental idea and creative powers.

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The Modes of Existence for the Housewife's Authority in Joseon Dynasty (조선시대 부권(婦權)의 존재 양상 연구)

  • Lee, Eun-Bong
    • (The)Study of the Eastern Classic
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    • no.73
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    • pp.65-89
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    • 2018
  • This paper was triggered by the idea that the culture of ancestral rites and the patrilocality, which entail the excessive sacrifice on the part of the wife, that eventually led to the coinage of the expression, "housewives' holiday stress," is perhaps not the age-old traditions it claim to be, but rather a recent phenomenon. The purpose of this paper is to reveal that the loss of housewife's authority is the product of "becoming yangban (aristocrats)," which was a culture that was in fashion in the late Joseon dynasty. Until the late Joseon dynasty, women, in particular, the married women maintained an autonomous life which allowed them the authority to an extent, based on their properties that they brought from and the ties that they maintained with their original family and. However, such authority of the housewives disappeared since the invasion of Joseon by Japan and Qing in the year of Imjin (1592) and Byeongja (1636), respectively, as the daughters were excluded from receiving inheritance in a desperate attempt to maintain the impoverished family after the wars. However, patriarchy based on neo-Confucian custom and convention of patriarchal clan system could not spread to the entire population immediately after the wars, as it was impossible to include everyone in the aristocratic class (yangban). It was due to the increase of aristocrats within the continued social changes that occurred after the wars that the neo-Confucian patriarchy became the norm and ethical standard in Joseon society. Also, the theory of propriety in neo-Confucianism that everyone from the emperor down to commoners must abide by the patriarchal clan system was realized through Zhuzi jiali, i.e. Master Zhu's Family Rituals, which institutionalized the system of family rites by setting up ancestral shrines in every household. For the aristocrats who lost their financial footing, the only basis they could rely on to prove their aristocratic lineage is the strict compliance with the rituals. Also, for the once commoners who turned into aristocrats one day had to emphasize the formal propriety in order to distinguish themselves from the commoners. Hence, the culture of "becoming yangban" in the nineteenth-century Joseon was what solidified the patriarchal rituals, decorum, and clan system. As a result, women have become subordinated to the husband's families, which forced the women, i.e. the housewives to serve them and sacrifice themselves for them. At times, women self-imposed such restraints on them as they led themselves into believing that it was necessary to maintain the family for their sons.