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Propagation and attenuation of elastic waves in the submarine layers (Part I) (해저퇴적층(海底堆積層)에서의 탄성파(彈性波)의 전파(傳播)와 감쇠(減衰))

  • Song, Moo Young;Park, Yong Ahn
    • Economic and Environmental Geology
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    • v.9 no.4
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    • pp.213-223
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    • 1976
  • Proceeding from general elementary principles to more specific abstract problems, we have attempted the rearrangement of the research results as they are known at present concerning the propagation and attennation of the elastic wave in submarine layers. We have derived the elementary equations of the elastic wave. In addition, the relationship of the propagation of the elastic waves in the sea water mass and the reflection of the waves from the water-sediment interface are treated and presented in different sections.

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Developing a Questionnaire to Evaluate the Healthy Restaurant Program (건강식당사업 효과평가를 위한 조사지 개발)

  • Hong, Kyung-Eui;Joung, Hyo-Jee
    • Journal of Nutrition and Health
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    • v.44 no.6
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    • pp.562-576
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    • 2011
  • The purpose of this study was to develop a reliable questionnaire to assess the effectiveness of the healthy restaurant program, which was implemented by Seocho-gu District in Seoul. Evaluation indices were deduced from the logic model of the healthy restaurant program. The questionnaires consisted of three sections (process evaluation, outcome evaluation, and general characteristics) for restaurateurs and customers who were participating in the program or not. To validate the questionnaire, 133 restaurateurs and 246 customers were sampled using convenient methods. Data were collected by interviews. Reliability was tested by Cronbach's alpha coefficient. The alpha coefficient for restaurateurs was 0.75-0.99 for the process and 0.79-0.97 for the outcome evaluation questions. The alpha coefficients for customers were 0.76-0.92 for the outcome evaluation questions. Face and content validity were examined for all questions, and construct validity was tested for latent variables. We are confident that more accurate and significant information will be collected using this questionnaire.

Hydrodynamic Masses of HANARO Flow Tubes (하나로 유동관의 동적유체질량)

  • 류정수;김두기
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.4
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    • pp.413-422
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    • 2001
  • In this study, the effect of hydrodynamic masses is investigated in the dynamic characteristics and earthquake response analyses of the submerged HANARO flow tubes. First, the consistent hydrodynamic masses of the surrounding water are obtained by finite element method. Then, modal analyses and response spectrum analyses are performed and verified by comparing the results with those measured from an experiment. Arbitrary cross-sections of submerged structures and boundary conditions of the surrounding fluid can be considered by using the general benefits of a finite element method comparing with the conventional analytical methods. Practical criteria based on parametric studies are proposed to evaluate the dynamic characteristics of HANARO flow tubes including the hydrodynamic masses.

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An Implementation of an Courseware Authoring Tool Using a Concept based Courseware Representation Method (개념 기반의 코스웨어 표현 방법과 이를 이용한 인터넷 기반의 코스웨어 저작 도구의 구현)

  • Kim, Man-Seok;Kim, Chang-Hwa
    • The Journal of Korean Association of Computer Education
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    • v.5 no.2
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    • pp.39-48
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    • 2002
  • It is general that the ICAI(Intelligent Computer Assisted Instruction) consists of 4 modules. Export module, Teacher module, Student module and Interface module. In each module construction, there should be some rules to control strategies efficiently and systematically that are related to the texts and assessment instruments, assessment results and evaluation, feedback, etc. It is necessary to use a method to classify the curriculum into sections with units and to represent the identified relationships between them. These relationships are available to all the process of learning, assessment, evaluation and feedback. In this paper, we propose the method to represent these units and relationships as a graph. In addition, we implement an internet-based courseware authoring tool to support the environment in which several expert can construct concurrently the courseware with cooperation between them.

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The Effects of Science Lessons Using Creative Activities on Scientific Concepts and Self Directed Learning Ability (창의적 체험활동 프로그램이 과학개념 및 자기주도적 학습능력에 미치는 효과)

  • Lee, Yongseob;Kim, Yoonkyung
    • Journal of the Korean Society of Earth Science Education
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    • v.8 no.3
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    • pp.399-408
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    • 2015
  • This study is to find out that the effects of a creative experience activity program to scientific concepts and self-directed learning skills. This study has been aimed at 2 class 40 students of 4th grade in D metropolitan city A elementary school in 2015, one class 20 students are the research group to apply Scientific research program using creative experience activity, another class 20 students were comparison groups to apply general science classes. The related class section of this study is 4th grade 2 semester of science 4 chapters, 'The Earth and the moon' This section is in fourth grade elementary science curriculum revision in 2009 is a Sections to learn for the first time about astronomical area. Target research group in club activities as part of the creative activities implemented using scientific inquiry and analyzed the results. In addition, in order to better research based on the results of this study as follows. First, the science curriculum in elementary schools, as well as applied research about the creative experience activity classes in other subjects is required. The ongoing research is needed to classes utilizing the characteristics of creative experience activities in several subjects of the elementary school curriculum. Second, Creative experiential learning is only effective when it is done consistently, it is worth studying for long periods of time.

Designing the Space under the Urban Elevated Road -A Case Study for Nengdong-Ro Street- (도시고가도로 입지구간 가로환경 설계 -능동로 '걷고싶은 거리'의 구간을 대상으로-)

  • 진양교;홍윤순
    • Journal of the Korean Institute of Landscape Architecture
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    • v.28 no.1
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    • pp.136-146
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    • 2000
  • Although the urban elevated road is welcomed in modern society to deal with urban traffic problems, its negative influence on both the pedestrian environment and urban landscape has been frequently observed. Furthermore, the space under elevated structures has been ignored, being the lost space. Recently, several efforts have been devoted into bringing back the lostspace. However, any specific design guidelines shown in the street design of Japan and Singapore have not been suggested in Korea, yet. This study proposes a case of the Nengdong-Ro street design where the two-story urban elevated road is being constructed and negative effects of the elevated road are largely expected. One of the purposes of Nengdong-Ro street design proposed in this study is to relieve the negative effect os the two-story elevated road, and to provide a better pedestrian environment in Nengdong-Ro. The other purpose is to suggest general guidelines that can be applied to the similar context as Nengdong-Ro. It is considered that the space under the elevated road generally consist of three sections: 1) main section where the elevated road runs parallel with the ground, 2) landing section where elevated road goes down to the ground, and 3) facility section where facilities such as the platform and the ticketing booth are located. The design guidelines are suggested for each section, because each section has a different situation. Plans, section and elevations and the details of the street furniture are also incorporated to support the design guidelines.

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Computation of Viscous Flows around a Two-dimensional Oscillating Airfoil ( Part 1. without Dynamic Stall ) (진동하는 2차원 날개 단면 주위에 대한 점성 유동장 계산( Part 1. 동적실속이 없는 경우 ))

  • Lee, Pyoung-Kuk;Kim, Hyoung-Tae
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.1 s.151
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    • pp.8-15
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    • 2007
  • In this paper, numerical calculations are performed to analyze the unsteady flow of NACA airfoil sections. In order to ease the flow computation for the fluid region changing in time, improve the quality of solution and simplify the grid generation for the oscillating foil flow, the computational method adopts a moving and deforming mesh with the multi-block grid topology. The multi-block, structured-unstructured hybrid grid is generated using the commercial meshing software Gridgen V15. The MDM (Moving & Deforming Mesh) and the UDF (User Define function) function of FLUENT 6 are adopted for computing turbulent flows of the foil in pitching motion. Computed unsteady lift and drag forces are compared with experimental data. in general, the characteristics of unsteady lift and drag of the experiments are reproduced well in the numerical analysis.

Sectional Forming Analysis of Automobile Sheet Metal Parts by using Rigid-Plastic Explicit Finite Element Method (강소성 외연적 유한요소법을 이용한 자동차 박판제품의 성형공정에 대한 단면해석)

  • Ahn, D.G.;Jung, D.W.;Yang, D.Y.;Lee, J.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.3
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    • pp.19-28
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    • 1995
  • The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solutions since it improves the convergency problem, memory size and computational time especially for the case of complicated geometry and large element number. The explicit schemes in general use are based on the elastic-plastic modelling of material requiring large computation time. In the present work, rigid-plastic explicit finite element method is introduced for analysis of sheet metal forming processes in which plane strain normal anisotropy condition can be assumed by dividing the whole piece into sections. The explicit scheme is in good agreement with the implicit scheme for numerical analysis and experimental results of auto-body panels. The proposed rigid-plastic explicit finite element method can be used as robust and efficient computational method for prediction of defects and forming severity.

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Experimental Study and Correlation Development of Critical Heat Flux under Low Pressure and Low Flow Condition

  • Kim, Hong-Chae;Baek, Won-Pil;Kim, Han-Kon;Chang, Soon-Heung
    • Proceedings of the Korean Nuclear Society Conference
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    • 1997.05a
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    • pp.356-361
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    • 1997
  • To investigate parametric effect on CHF and to get CHF data, experimental study has been performed with vertical round tubes under the condition of low pressure and low flow (LPLF). Test sections are made of Inconel-625 tube and have the geometry of 8 and 10 mm in diameter, and 0.5 and 1.0 m in heated length. All experiments have been conducted at the pressure of under 9 bar, the mass flux of under 250 kg/$m^2$ and the inlet subcooling of 350 and 450 kJ/kg, for stable upward flow with water as a coolant. Flow regime analysis has been performed for obtained CHF data with Mishima's flow regime map, which reveals that most of the CHF occur in the annular-mist flow regime. General parametric trends of the collected CHF data are consistent with those of previous studies. However, for the pressure effect on CHF, two different are observed; For relatively high mass flux, CHF increases with pressure and far lower mass flux, CHF decrease with pressure. Using modern data regression tool, ACE algorithm, two new CHF correlations for LPLF condition are developed based on local condition and inlet condition, respectively. The developed CHF correlations show better prediction accuracy compared with existing CHF prediction methods.

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Definition of an Integrated Contract Package for Application of Multi-Trade Subcontract System (다공종 통합발주방식 적용을 위한 통합공종 규명에 관한 연구)

  • Song Hyung-Suk;Kim Kyoon-Tai;Han Choong-Hee;Kim Sun-Kuk
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • autumn
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    • pp.385-388
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    • 2002
  • The construction industry has complicated production processes with diverse disciplines and subcontractors, which is the major cause of lowered productivity. To solve this problem, multi-trade subcontract system is recently suggested. Some general construction companies have applied this method to some sections of work process. However, this is in the early stage of application. The purpose of this study is to define an integrated contract package for improving both contractor and subcontractor efficiency. First, this study recognizes construction company to need of multi-trade subcontract system. Finally, it suggests feasible activities which can be useful for a construction company to apply to this subcontract system.

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