• Title/Summary/Keyword: Rational

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LRFD Design and Reliability Level Estimation of a Steel Closed-Box Girder Bridge (폐단면 강박스거더교의 LRFD 설계와 신뢰성수준 평가)

  • Huh, Jung-Won;Yun, Dong-Geon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.2
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    • pp.217-225
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    • 2010
  • Most of the steel bridges in Korea are being currently designed by the allowable stress design method that uses the conventional deterministic factors of safety. However the limit state design based on the concept of probability, statistics and reliability engineering is becoming very popular as a global standard deign method, leading the rational and economic bridge design. As part of the fundamental research to establish the load and resistance factor design(LRFD) of steel bridges considering domestic environmental conditions and regional characteristics, an experimental design is conducted by applying AASHTO-LRFD specification especially to a steel closed-box girder, which occupies relatively a large portion of steel bridges in Korea. Throughout the experimental design according to various sectional changes, some of the issues to be considered in the LRFD design of a composite steel closed-box girder bridge are examined. In this process, an Excel-based design verification program is developed for easy computation and prevention of errors. Quantitative reliability levels of the bridge sections designed by LRFD are also estimated using a reliability analysis method, and compared with the target reliability indexes applied in the LRFD design to verify the validity of the procedure and methodology used in this study.

A Study on Trade Automation in Korea (한국의 무역자동화에 관한 고찰)

  • 전재경;이재승
    • Journal of the Korea Society of Computer and Information
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    • v.3 no.3
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    • pp.139-150
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    • 1998
  • Due to development of science and telecommunication with wide-spread computer supply, it could be done through computer automatically instead of manpower-work for paper transportation & paper approval. It is developed to so-called Factory Automation. Further, it is developed to Office Automation. Trading companies & concerned trade authorities are interested in Trade Automation that such technique is applied to trade work. Generally, Trade Automation means to realize paperless trade by exchanging electronic papers through inter-computers after concerned trade operators transformed various papers to electronic papers that computer could read. In case Trade Automation fix in the trade business, it is expected one of innovations among traditional paper work of trade business, namely without going import-export authorities, Customs office, Banks. Shipping companies, Marine insurance companies on hand-carrying papers, it could be fast, simple, correct to finish every trade procedures such as commercial business, foreign currency, customs clearance, transportations, insurance. terms of payment, etc., with Electronic Data Interchange through computer facilities. Especially, telecommunication for trade form could be helpful to proceed trade paper with one-run-method Further we can anticipate 6 effects for Trade Automation as belows : First, as explained just above articles, with completion for Trade Automation, every trade procedures can be done by computer. so, time to work can be diminished. namely. logistics cost including accessory costs for trade procedures can be saved much. Second, viewing to private enterprise, effect of Office Automation can be maximized and rapid, correct exchange for various trade informations could raise efficiency of enterprise management establishing rational production, storage, transportation and could raise competition improving standard for consumers's service. Third, establishing Trade Automation systems makes it easier piling-up of harbor cargo by pre-transmission of electronic paper & trade informations make it possible to finish customs clearance in advance and can be dispatched upon cargo arrival. Fourth, most of concerned trade authorities such as import-export approval office. financial authorities, transport & insurance companies concentrated in Metropolitan area(Seoul, In -Cheon, Kyung-Ki). Therefore, in case Trade Automation could be realized. it is possible to proceed trade business instantly in every country area by computer facilities. Also. it contribute well-balanced development for suburb. region area by suburb dispersion of trading companies. Fifth, on the way to Trade Automation establishment & its enlargement process. producing enormous demand for over-all telecommunication such as hardware. software. network makes opportunity to progress telecommunication industry & concerned industries. Finally. Trade Automation accelerate change of employment structure leading unnecessary labors on the industries of office & logistics to manufacturing area.

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Test and Analysis on the Transverse Gusset Plate Connection to Circular Hollow Section(CHS) of High Strength (고강도 원형강관의 직각방향 거셋플레이트 접합부 실험 및 해석)

  • Lee, Swoo-Heon;Shin, Kyung-Jae;Lee, Hee-Du;Kim, Woo-Bum
    • Journal of Korean Society of Steel Construction
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    • v.24 no.2
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    • pp.163-173
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    • 2012
  • A connection composed of a circular hollow structural section (HSS) has complicated details, and exhibits a very complex local deformation when it reaches the yield stress. Given these circumstances, proposing a simple design equation considering local deformation is difficult. The design equations of the Korea Building Code (KBC 2009) for HSS joints are simple and are very similar to those of the AISC. These design equations limit the maximum yield stress up to 360MPa and yield ratio (yield strength/tensile strength) up to 0.8. This means that the material with yield strength exceeding 360MPa could be used after verification based on the test or rational analysis for the similar connection. This paper introduces an experimental program and finite element analysis (FEA) for the circular hollow section (CHS) with a transverse gusset plate made of high-strength steel (HSB600) or structural steel (SS400) when the joints are subjected to lateral force. Comparison of the design equations with the results of FEA and test may be used for the modification of the design equations.

A Study on the Rational Application of 3D Numerical Analysis for Anchored Earth Retaining Wall (앵커지지 흙막이 벽체의 합리적인 3차원 수치해석기법 적용에 관한 연구)

  • Jeong, Sang-Seom;Sim, Jae-Uk;Lee, Sung-June
    • Journal of the Korean Geotechnical Society
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    • v.32 no.4
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    • pp.29-39
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    • 2016
  • This paper presents the results of 2D and 3D finite element simulations conducted to analyze the effects of excavation depth (H), excavation width (L), and ground condition on the behavior of anchored earth retaining wall in inclined ground layers. The results of numerical analyses are compared with those of the site instrumentation analyses. Based on the results obtained, it appeared that 2D numerical analysis tends to overestimate the horizontal displacement of retaining wall compared to the 3D numerical analysis. When the excavation depth is deeper than 20m, it is found that 2D and 3D numerical analysis results of excavation work in soil ground condition are more different from the results in rock ground condition. For an accurate 3D numerical analysis, applying 3D mesh which has an excavation width twice longer than excavation depth is recommended. Consequently, 3D numerical analysis may be able to offer significantly better predictions of movement than 2D analysis.

The Relationship between Organizational Culture, Job Characteristics and Job Continuance among Police Officers (경찰공무원의 조직문화와 직무특성 및 직무지속의지의 관계)

  • Kim, Chan sun;Park, Young Man
    • Convergence Security Journal
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    • v.14 no.6_2
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    • pp.63-72
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    • 2014
  • The purpose of this study is to investigate the relationship between organizational culture, job characteristics and job continuance will among police officers. This study targets the police officers dispatched in the Seoul metropolitan area in 2012, and it uses judgment sampling method to analyze 187 samples. This study conducted the statistical analysis, including frequency analysis, factor analysis, reliability analysis and multiple regression analysis, by using SPSS WIN 18.0. The result is as follows. First, the organizational culture among police officers has effects on job characteristics. That is, the feedback increases as the organizational culture becomes more mutual development- or agreement-oriented, or as it becomes more hierarchical; on the other hand, the job importance increases as more hierarchical and rational a culture becomes. Also, self-determination increases as an organization becomes more mutual development- or agreement-oriented. Second, the organizational culture among police officers has effects on the job continuance will. That is, the expected satisfaction increases but intentional insincerity decreases as the organizational culture becomes more mutual development- or agreement-oriented. Also, risk-perceiving behavior increases as an organizational culture becomes more hierarchical. Third, police officers' job characteristics have effects on the job continuance will. That is, the feedback and job importance increases the expected satisfaction while reducing functional diversity. The feedback also reduces the contraction factor. The job importance increases intentional insincerity while reducing functional diversity. The functional diversity not only increase alternative expectation but also increases risk-perceiving factors.

Korean Strategies for Establishing New MRV Schemes Applicable to Post-2020 Regime (Post-2020의 MRV 체계 수립을 위한 우리나라 대응 방향)

  • Kim, Seungdo;Ryu, SeungYun;Jung, Jaehyuk;Yoo, Beom-Sik
    • Journal of Environmental Policy
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    • v.14 no.4
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    • pp.3-21
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    • 2015
  • This paper attempts to determine the most reasonable and agreeable option for new MRV framework in Post-2020 Climate Regime as well as to develop South Korea strategies to reflect our national circumstances and capacities appropriately. The options for MRV framework considered here are 1) Dual MRV and 2) Unified MRV. We reached the conclusion that the Unified MRV framework may be the most reasonable option in the 2015 agreement in line with the objectives of MRV. To this end, it is essential to develop effective stepwise strategies consisted of: 1) reaching a consensus internally on the Unified MRV framework, 2) developing detailed procedures and methodologies to make the major elements of the Unified MRV framework understandable and predictable, 3) delivering an overview and blueprint to make sure of the flexibility of the Unified MRV framework to reflect the Parties' capacities and national circumstances, 4) ensuring the financial and technical support schemes for developing countries to improve the capacity-buildings of MRV, and 5) developing a realistic road map to successfully implement the Unified MRV scheme within the required time frame. Korea, as a rational mediator between developed and developing countries, should play a leading role in reaching post-2020 agreement.

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The Problems for Application of Nursing Process in Clinical Experience of Nursing Students (임상실습에서 학생들이 경험하는 간호과정 적용문제)

  • Yang Young-Hee
    • The Journal of Korean Academic Society of Nursing Education
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    • v.5 no.1
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    • pp.58-71
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    • 1999
  • Nursing process is an essential part for nursing practice. Nursing faculty members must focus on the clinical application for students and try to identify the possible problems that students might face in the fields. The purpose of this study is to examine the actual condition of nursing process education in curricula and to investigate the response of students in clinical experience of nursing process. From 462 students in the 6 associate programs(ADN) and the 6 baccalaureate programs (BSN) data was collected by questionnaire. The results were as followed. 1. Seven programs (58.3%) opened the nursing process in mainly sophomore (BSN) or freshman(ADN). If not opened, the nursing process was taught at the major subjects(espcially fundamental nursing or adult nursing). 2. All Students responded they we supposed to use nursing process in preparing the case report. The majority(94.6%) used NANDA lists for nursing diagnosis and 55.7% of subjects consulted the Korean terms by KNA when translating. The tutors for nursing process in clinical settings were the professor in charge of the subject (68.6) or clinical instructors (48.1%) , assistants(34%). 3. The problems in clinical application that students experienced consisted of 17 items and the mean was 2.27. The biggest problem was 'the lack of the model for RN of applying the nursing process in clinical settings'(2.97). Next the big problem was 'the lack of the competency for implementing the established nursing plans'(2.69). All items were significantly different according to the level of educational programs(ADN or BSN). ADN students had more problems in applying the each step of nursing process and BSN students perceived the NANDA as a guidance of nursing diagnosis and the inconsistency of advices from several instructors or practicum to be mere problematic. 4. The mean of merits after application of nursing process was relatively fair (2.82). The best merit was 'they can identify nursing problems more exactly'(3.07). The second high merit was 'they can study the rational of nursing action' (3.03). BSN than ADN and the subjects of second year than of one year in clinical experience perceived the use of nursing process to be better. Based on this results we need to enforce the application of nursing diagnosis in the class. The use of sample cases can be the efficient method. Students can identify the possible health problems for patient from the cases in imaginary world and discuss them each other. Also we can use the discussion session after practice every other day or as needed. All this is on the good interaction between tutor and student. We must consider to have enough time for student to seize the essence of the nursing process.

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Experimental Study on Physical Properties of High-Strength Concrete Using Sea Sand (해사 사용 고강도 콘크리트의 물성에 관한 실험적 연구)

  • 정영수;배수호;박종협
    • Magazine of the Korea Concrete Institute
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    • v.8 no.3
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    • pp.219-229
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    • 1996
  • Recent construction activity of infrastructures has been booming and accelerating to incur shortage of river sand for concrete works. Thus, sea sand has been excessively used instead of river sa.nd, that directly causes to decrease the quality and the durability of concrete, and then might lead to the collapse of concrete structures. The purpose of this experimental research is not only to develop high-strength concrete using sea sand, but also to investigate mechanical properties of high-strength concrete, such as elastic moduli, compressive strength and etc, which could be used for important design data of concrete structures. Rational analytic formula for elastic moduli have been proposed together with those for the splitting tensile strength and the flexural strength, which are to be predicted from compressive strength of concrete cylinder. Optimum water-cement and water-binder ratio have been experimentally obtained so as to develop high compressive strength with and without using silica fume as a admixture for concrete. It is noted that experimental elastic moduli for high strength concrete above aCk=330kgf /cm2 are less than those by the Code. Appropriate amount of concrete mixture has been experimentally investigated so as to develop maximum compressive, flexural and splitting tensile strength.

Ultimate Stress of Unbonded Tendons in Post-Tensioned Flexural Members (포스트텐션 휨부재에서 비부착긴장재의 극한응력)

  • Lee, Deuck-Hang;Kim, Kang-Su
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.489-499
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    • 2009
  • It is quite difficult to predict the flexural strength of post-tensioned members with unbonded tendons (unbonded posttensioned members, UPT members) because of debonding behavior between concrete and prestressing tendons, which is different from that with bonded tendons. Despite many previous researches, our understanding on the flexural strength of UPT members is still insufficient, and thus, national codes use different methods to calculate the strength, which quite often give very different results. Therefore, this paper reviews various existing methods, and aims at proposing an improved rational strength model for UPT flexural members having better accuracy. Additionally, a database containing a large number of test data on UPT flexural members has been established and used for verification of the proposed flexural strength model. The analysis results show that the proposed method provides much better accuracy than many existing methods including the rigid-body model that utilizes the assumption of concentrated deformation and plastic hinge length, and that it also gives proper consideration on the effects of primary parameters such as reinforcement ratio, loading pattern, concrete strength, etc. Especially, the proposed method also well predicts the ultimate stress of unbonded tendons of over-reinforced members, which are often possible in construction fields, and high strength concrete members.

Fiber Orientation Factor on a Circular Cross-Section in Concrete Members (콘크리트 원형단면에서의 섬유분포계수)

  • Lee, Seong-Cheol;Oh, Jeong-Hwan;Cho, Jae-Yeol
    • Journal of the Korea Concrete Institute
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    • v.26 no.3
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    • pp.307-313
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    • 2014
  • In order to predict the post-cracking tensile behavior of fiber reinforced concrete, it is necessary to evaluate the fiber orientation factor which indicates the number of fibers bridging a crack. For investigation of fiber orientation factor on a circular cross-section, in this paper, cylindrical steel fiber reinforced concrete specimens were casted with the variables of concrete compressive strength, circular cross-section size, fiber type, and fiber volumetric ratio. The specimens were cut perpendicularly to the casting direction so that the fiber orientation factor could be evaluated through counting the number of fibers on the circular cross-section. From the test results, it was investigated that the fiber orientation factor on a circular cross-section was lower than 0.5 generally adopted, as fibers tended to be perpendicular to the casting direction. In addition, it was observed that the fiber orientation factor decreased with an increase of the number of fibers per unit cross-section area. For rational prediction of the fiber orientation factor on a circular section, a rigorous model and a simplified equation were derived through taking account of a possible fiber inclination angle considering the circular boundary surface. From the comparison of the measured data and the predicted values, it was found that the fiber orientation factor was well predicted by the proposed model. The test results and the proposed model can be useful for researches on structural behavior of steel fiber reinforced columns with a circular cross-section.