• Title/Summary/Keyword: core moment

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EFFECT OF BASE FLOW AND TURBULENCE ON THE SEPARATION MOTION OF STRAP-ON ROCKET BOOSTERS (기저부 유동 및 난류가 다단 로켓의 단 분리 운동에 미치는 영향)

  • Ko, S.H.;Kim, J.K.;Han, S.H.;Kim, J.H.;Kim, C.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.83-86
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    • 2007
  • Turbulent flow analysis is conducted around the multi-stage launch vehicle including base region and detachment motion of strap-on boosters due to resultant aerodynamic forces and gravity is simulated. Aerodynamic solution procedure is coupled with rigid body dynamics for the prediction of separation behavior. An overset mesh technique is adopted to achieve maximum efficiency in simulating relative motion of bodies and various turbulence models are implemented on the flow solver to predict the aerodynamic forces accurately. At first, some preliminary studies are conducted to show the importance of base flow for the exact prediction of detachment motion and to find the most suitable turbulence model for the simulation of launch vehicle configurations. And then, developed solver is applied to the simulation of KSR-III, a three-stage sounding rocket researched in Korea. From the analyses, after-body flow field strongly affects the separation motions of strap-on boosters. Negative pitching moment at initial stage is gradually recovered and a strap-on finally results in a safe separation, while fore-body analysis shows collision phenomena between core rocket and booster. And a slight variation of motion is observed from the comparison between inviscid and turbulent analyses. Change of separation trajectory based on viscous effects is just a few percent and therefore, inviscid analysis is sufficient for the simulation of separation motion if the study is focused only on the movement of strap-ons.

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Optimum Structural Design of Sandwich Plates Considering the Shear Buckling (전단 좌굴을 고려한 샌드위치 평판의 최적 구조 설계에 관한 연구)

  • C.D. Jang;M.S. Cho
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.3
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    • pp.56-65
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    • 1996
  • Recently, with development of mechanics of materials, as pursuing the high speed of the ships, there has been an increasing demand on the composite construction which satisfies high strength and low weight at the same time. A sandwich element is a type of composite construction, which is composed of thin, strong, stiff and relatively high density faces and a thick, light, and weaker core material. As the second moment is increased by faces separated from the neutral axis farther, a sandwich element is most effective light structural form. In this study, Rayleigh-Ritz Energy Method is adopted, which can analyze sandwich plate relatively simply and exactly. Stresses and buckling loads are analyzed exactly, when uniform lateral pressure load, inplane compression and inplane shear are acting at the sandwich plate. Including a wrinkling stress, this study can be applied to the initial design and minimum weight design of sandwich plates.

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Seismic Characteristics of Hollow Rectangular Sectional Piers with Reduced Lateral Reinforcements (횡방향철근이 감소된 중공사각단면 교각의 내진거동 특성)

  • Sun, Chang-Ho;Kim, Ick-Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.3
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    • pp.51-65
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    • 2009
  • The seismic design concept of RC bridges is to attain the proper ductility of piers, yielding a ductile failure mechanism. Therefore, seismic design force for moment is determined by introducing a response modification factor (R), and lateral reinforcements to confine core concrete are specified in the current design code. However, these design provisions have irrationality, which results in excessive amounts of lateral reinforcements for columns in Korea, which are generally designed with large sections. To improve on these provisions, a new design method based on seismic performance has been proposed. To apply this to hollow sectional columns, however, further investigations and improvements must be performed, due to the different seismic behaviors and confinement effects. In this study, hollow sectional columns with different lap-splice of longitudinal bars and lateral reinforcements have been tested. Seismic characteristics and performance were investigated quantitatively. These research results can be used to derive a performance-based design for hollow sectional columns.

An Empirical Study on the Quality Management for Port Services - Primarily on Container Terminals in Busan - (항만서비스품질경영에 관한 실증연구 - 부산항 컨테이너터미널을 중심으로 -)

  • Choi, Young-Ro;Shin, Han-Won;Ko, Su-Bok
    • Journal of Navigation and Port Research
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    • v.26 no.2
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    • pp.153-159
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    • 2002
  • An empirical study was carried out to examine how Container Terminals in Busan view quality management activities by the provision of statistical evidence showing the efforts to enhance the standard of quality management, common factors of quality management activities and causal relationship among these factors. The data investigating the quality management for Busan Container Terminals were collected from 170 persons in charge of quality management for port services in Busan Container terminals by the use of questionnaire method and personal interviews. The Cronbach's a coefficient and factor analysis were used to analyze the reliability and the validity of measured variables. Furthermore, SEM (Structural Equation Modeling) method using AMOS(Analysis of MOment Structure) 4.0 was usea to analyze the cause-effect relationship among the source, activities and accomplishments of quality management representing the core concept of quality management system.

Eccentric Axial Loading Test for Concrete-Encased L-section Columns using 800MPa Steel and 100MPa Concrete (800MPa 강재 및 100MPa 콘크리트를 적용한 ㄱ형 강재 매입형 합성기둥의 편심압축실험)

  • Kim, Chang-Su;Park, Hong Gun;Lee, Ho Jun;Choi, In Rak
    • Journal of Korean Society of Steel Construction
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    • v.25 no.2
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    • pp.209-222
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    • 2013
  • Eccentric axial loading test was performed for concrete-encased columns using 800MPa steel and 100MPa concrete. To maximize the contribution of the high-strength steel, L-shaped steel sections were placed at four corners, and connected to each other by lattices, links, or battens. Compared to a H-section of the same area, the moment-arm and strain of the L-sections are increased. Also, the corner L-sections provide good lateral confinement to concrete core. The test results showed that the peak strength and effective flexural stiffness of the L-section columns were increased by more than 1.4 times those of the H-section column.

Thoughts on Chinese New Media Dance Triggered by the Use of 'Bullet Time' in the Premiere of "Dance Smash" (댄스 스매시 프로그램에 적용된 불릿타임의 효과와 중국 뉴미디어 무용의 과제)

  • Chen, Jinjing
    • Trans-
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    • v.8
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    • pp.79-93
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    • 2020
  • The main purpose of this article is to discuss the impact of "Dance Smash" TV show on Chinese dance, which uses the combination of dance and new media technology as the core content of the program. "Dance Smash", as a dance communication TV program for the public, first considers the entertainment attributes of variety shows. Spread the dance art on the basis of meeting the public's aesthetic needs, thereby expanding the popular living space of dance art. The use of 'moment of the storm' has let the general audience of non-dance majors feel the technical charm of dances, thus playing a healthy promotion role. However, whether "Bullet Time", a type of dance program that has had a successful case in the West, can also have a positive impact on the mass communication of dance in the localization of China, this is what questions and seeks of this article.

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Correlations between the Muscle Thickness of the Transverse Abdominis and the Multifidus Muscle with Spinal Alignment in College Students (대학생의 배가로근과 뭇갈래근 두께와 척추정렬간의 상관관계)

  • Lim, Jae-Heon
    • PNF and Movement
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    • v.12 no.4
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    • pp.243-248
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    • 2014
  • Purpose: The transverse abdominis and themultifidus muscle are located in the core. They surround one's trunk and help in body stabilization. Specifically, they control spine articulation to maintain posture and balance. Therefore, weakened deep muscle in the trunk may cause spinal malalignment. This study aims to compare the correlation between the thickness of the transverse abdominis and the multifidus muscle and the spine alignment among college students in their 20s. Methods: This study measured the thickness of the transverse abdominis and the multifidus muscle of 42 healthy college students in their 20s using ultrasonic waves. The thickness of the muscle was measured for the length of the cross-section except for fascia. The thickness of the left and right muscles was measured, and the mean value was calculated. As the thickness of the transverse abdominis can increase because of pressure during exhalation, it was measured at the last moment of exhalation. Spinal alignment was measured by the kyphosis angle, lordosis angle, pelvic tilt, trunk inclination, lateral deviation, trunk imbalance, and surface rotation using Formetric III, which is a three-dimensional imaging equipment. They were measured for three times, and the mean values were calculated. The general characteristics of the subjects were analyzed using descriptive statistics. The correlations between each factor were analyzed using Pearson's correlation analysis. Results: The transverse abdominis showed asignificant correlation with trunk inclination (p<.05). The multifidus muscle showed a significant positive correlation with pelvic tilt and a negative correlation with surface rotation (p<.05). Conclusion: The thickness of transverse abdominis and the multifidus muscle appears to influence spinal alignment. Specifically, the multifidus muscle, which plays an important role on the sagittal plane, influences surface rotation, thus making it an important muscle for scoliosis patients. Therefore, a strengthening training program for the transverse abdominis and the multifidus muscle is necessary according to specific purposes among adults with spinal malalignment.

A Study on Makerspace: Focusing on Its Urbanism and Placeness (산업공간으로서 메이커스페이스의 도시성(urbanism)과 장소성(placeness))

  • Jeong Seok Ha
    • Journal of the Economic Geographical Society of Korea
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    • v.25 no.4
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    • pp.547-567
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    • 2022
  • In this study, I focus on makerspaces, which have rapidly spread since the late 2000s in the world's major cities. Makerspaces, born amid great social change, reflect the core characteristics of industrial space. I analyze the makerspace based on the theoretical perspectives of urbanism in the macroscopic aspect and placeness in the microscopic aspect. The urbanism of makerspaces is manifested through entry into the inner cities and their connections with urban capabilities. This means that convergence with innovation factors is becoming more important than optimization of factor costs and agglomeration economies in the locational determinants of industrial space. The placeness of makerspaces is being re-formed through an emphasis on taste, the expansion of autonomy, and the strengthening of connections. This reveals how the value creation process within the industrial space is changing, from forming-placelessness through standardization, uniformity, and compartmentalization to forming-placeness through restoration of individual humanity and interaction. The results of the urbanism and placenesss analysis carry implications for the present moment, when it is necessary to diversify the spatial planning of industrial spaces.

Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.381-386
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    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

When sense, liturgy, and story meet children's spirituality (감각, 예전, 이야기가 어린이영성과 만날 때)

  • Kum Hee Yang
    • Journal of Christian Education in Korea
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    • v.76
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    • pp.27-49
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    • 2023
  • Purpose of study: The purpose of this paper is to gain insight into the alternative possibility of Christian children's education overcoming the current church school paradigm namely schooling system by examining the characteristics and the direction of children's spiritual education. Research content and method: This paper is a review of the characteristics of children's spiritual education and ways to embody those characteristics. Therefore, it consists of two parts: the characteristics of children's spiritual education and the search for ways to embody those characteristics. First, children's spiritual education is a "formative" model that aims to form children's spirituality based on children's spirituality research that views children as 'spiritual beings.' This model specifically has three core orientations: 'experience', 'meeting God', and 'immersion'. In other words, children's spiritual education pursues 'experience rather than knowledge', pursues the experience of meeting God in the second person rather than teaching third-person knowledge about God, and values the spiritual moment of immersion more than anything else. Second, it searches for specific ways and methods through which those three core goals could be implemented, and found that they were 'sense,' 'liturgy,' and 'story.' The sense becomes a path that evokes experience, the liturgy becomes a place for 'meeting God,' and 'story' becomes a key path to 'immersion.' And when the three are organically combined with each other, the goals pursued by children's spiritual education can be holistically converged. Conclusions and Suggestions: Through these considerations, it found that the core values and direction of education are consistently maintained in children's spiritual education, from children's understanding to education methods. It also figured out that the direction should be shared not only by children's spiritual education but also by all who pursue holistic faith education: 'what to experience' rather than 'what to teach', 'liturgy' rather than 'teaching', 'story' rather than 'explanation', and 'sensory' experiences rather than 'abstract' knowledge.