• 제목/요약/키워드: pulling

검색결과 473건 처리시간 0.03초

원심모형실험을 이용한 모래지반에 관입된 계류선 거동 평가 (Evaluation of Behaviors on Mooring Line Embedded in Sand Using Centrifuge Test)

  • 이훈용;김수린;김재현;김동수;추연욱;권오순
    • 한국해양공학회지
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    • 제28권1호
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    • pp.47-54
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    • 2014
  • When an anchor penetrates and is installed under a seabed, a portion of the mooring line connected to the anchor is also embedded under the seabed. This embedded mooring line affects the capacity of the anchor in two ways. First, the frictional resistance that occurs between the mooring line and the seabed reduces the pulling force acting on the anchor. Second, the embedded part of the mooring line forms a reverse catenary shape due to the bearing resistance of the soil, so that an inclined pulling force is applied to the anchor. To evaluate the mooring line's effect on the capacity of an anchor in sand, centrifuge model tests were performed using two relative sand densities of 76% and 51% while changing the anchor depths. The test results showed that the load is reduced much more in deep and dense sand, and the inclination angle of the load is lower in shallow and loose sand.

$YCa_4O(BO_3)_3$ 비선형광학 단결정 성장 및 Second Harmonic Generation 소자 제조에 관한 연구 (Crystal Growth of $YCa_4O(BO_3)_3$ and Preparation of Device for Second Harmonic Generation)

  • 유영문;;장석종;장원권;임기수
    • 한국결정학회지
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    • 제11권1호
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    • pp.16-21
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    • 2000
  • (Yb/sub x/Y/sub 1-x/)Ca₄O(BO₃)₃ single crystals where x=0.3,8,15,20% were grown by Czochralski Method. The crystals grown under the optimum conditions were transparent and colorless with good crystal form. Using polarizing microscope, crystal defects such as parasite crystals and bubbles were detected depending on the composition of melts and pulling rates. The optimum growth parameters for high quality of single crystals were 15∼20 rpm of rotation rate and 2mm/h of pulling rate at the flow rate of 2 l/min of Nitrogen gas. The relationship between crystal axes and optical axes was investigated by optical crystallographic method, polarization technique and single crystal X-ray method. From the spectroscopic measurements, it was confirmed that there were strong absorption bands at 900 and 976.4 nm and strong emission band at 976.4 nm in Yb/sup 3+/ ion doped YCa₄O(BO₃)₃ crystal. For the application of second harmonic generation of 1.064 ㎛ laser, non-linear optical devices with θ=32.32° and Ψ=0°, λ/10 of flatness and the size of 6x8x5.73 mm were fabricated from the grown YCa₄O(BO₃)₃ crystal.

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부엌공기 중에 함유되어 있는 가스량과 부엌 구조시설 연료관리와의 관계에 대한 연구 (A Study on the amount of Co gas in the kitchen related to facility enviromental condition and fuel management)

  • 장명욱
    • 대한가정학회지
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    • 제8권1호
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    • pp.146-158
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    • 1970
  • It is a matter of amazing to realize that contamination of air by fuel gas in recent daily life at home directly effects to health of Korean housewives. A study in finding the status and the amount of co gas in the kitchen was con-ductedrelating the size of kitchen, door of exit, ventilation window, constraction of built in-brick stove (Boo Tu Mack), fuel management, in order to extend beneficial and improved management of housing. From the result of study, it was pointed out that constractional improvement of built-in-brick stove, heating floor (Ondol), timny, and ventilation window would been emergently needed. Demonstration studies were obtained in finding differences of the amount of co gas respectively in cooking time as 50-55ppm, and in not cooking time as 50-80p,p,m in the kitchen both, original and improved. Definite differences were found depend upon the condition with, without, or direction of the ventilation window. In addition to all above results, significant influence on gas pulling power of Ondol tunnel was shown. Many houses of Apartment house for have middle and low income groups been recognized so poor for health as indicated over 100ppm of co gas if window were not opened because of poor ventilation and weak gas pulling power of Ondol tunnel.

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수정된 부유띠결정성장법에서 결정봉의 회전이 유동 및 열전달에 미치는 효과 (Effects of the crystal rotation on heat transfer and fluid flow in the modified floating-zone crystal growth)

  • 서정세
    • 대한기계학회논문집B
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    • 제20권10호
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    • pp.3322-3333
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    • 1996
  • A numerical analysis has been conducted to investigate a modified floating-zone crystal growth process in which most of the melt surface is covered with a heated ring. The crystal rod is not only pulled downward but rotated around its axisymmetric line during crystal growth process in order to produce the flat interface of crystal growth and the single crystal growth of NaNO3 is considered in 6mm diameter. The present study is made from a full-equation-based analysis considering a pulling velocity in all of solid and liquid domains and both of solid-liquid interfaces are tracked simultaneously with a governing equation in each domain. Numerical results are mainly presented for the comparison of the surface shape of rotational crystal rod with that of no-rotational crystal rod and the effects of revolution speeds of the crystal rod. Results show that the rotation of crystal rod produces more its flat surface. In addition, the shape of crystal growth near the centerline is more concaved with the increase in the revolution speed of crystal rod. The flow pattern and temperature distribution is analyzed and presented in each case. As the pulling velocity of crystal rod is increasing, the free surface of the melt below the heated ring is enlarged due to the crystal interface migrating downward.

금속과 고분자 재료의 접합강도 해석 (Analysis of Joining Strength in Electromagnetic Joining of Metals to High Toughness Polymers)

  • 손희식;김남환;이종수
    • 한국정밀공학회지
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    • 제9권3호
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    • pp.110-116
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    • 1992
  • Electromgnetic joining of aluminum alloy tubes to high toughness polyurethane rubber cores is studied in order to estimate the joining strength and to analyze the effect of the process variables. The equation which can estimate the joining strength is proposed under considering the elastic recovery of the polyurethane core and the radial shrinkage of the core by pulling it axially. The obtained results are as follows : 1) The joining strength is mainly dependent on the magnitude of residual elastic strain of the polyurethane core. 2) The radial shrinkage (residual strain reduction) of the core during the axial pulling causes the joining strength to decrease severely. The equation for the reduced axial strength is proposed and it is found that the estimated values agree well with experimental results. 3) The magnitude of radial shrinkage could be reduced for the smaller value of ratio l/r. 4) The joining strength in metal/polymer joining increases as the friction coefficient increases. But its effect of friction coefficient is insignificant in comparison with the case of metal/metal joining.

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삼각트랙을 구비한 외벽 등반로봇 플랫폼의 안정성 및 이동성 향상을 위한 토크 분배 알고리즘 개발 (Development of a Torque Distribution Algorithm for Improving Stability and Mobility of the Wall-climbing Robot Platform (ROPE RIDE) Equipped with Triangular Track Wheels)

  • 조선미;서근찬;김태균;김종원;김화수
    • 한국정밀공학회지
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    • 제30권7호
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    • pp.725-732
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    • 2013
  • This paper presents a torque distribution algorithm for improving the stability and mobility of a wall-climbing robot platform. During ascent, the pitch moment caused by the payload or external disturbances separates the robot's triangular tracks from the wall, significantly deteriorating its stability. Moreover, the reaction forces stemming from the increase in the pulling force may degrade the robot's mobility. Thus, it is very important to minimize the reaction forces acting on the triangular tracks, as well as the fluctuations in the pulling force, during the climb. Through dynamic modeling of the proposed robot platform, we demonstrated the dependence of the robot's stability and mobility on the torque distribution of the triangular tracks. Extensive simulations using different climbing speeds were used to significantly improve the stability and mobility of the proposed robot platform.

20세기 코르세트리의 구성 및 제작기법 (Immediate Constituent and Technics of Corsetry in the 20C)

  • 전혜정;김지연
    • 복식문화연구
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    • 제11권4호
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    • pp.562-577
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    • 2003
  • The object of my research is to inquiry into the immediate constituent and techniques of underwear after looking into basic theory of underwear, techniques by materials classified according to the matter of elasticity, and studying flat pattern and draping which are basis of corset and brassiere structure focusing on corsetry among underwears and production techniques. Various papers are referenced for theoretical study and the elements and techniques of underwear are analyzed based on photographical materials. This paper concludes as follows. To make the flat pattern of corset and brassiere fit to the body tightly, design dart two times without any space and draw smaller than the body. To support the breast sufficiently, move the side seam 1¼″ to the front panel and the seam should pass the apex in all occasions. For draping, dart should be added into short of elasticity materials in the past but dart is no use these days since the material today is extremely elastic. It is possible now to show the body line with only the seam or a pattern. In a case of elastic material, set the elastic direction to the grain line and have a draping as pulling from the center to the out side. As production technic, for an hem, put a zigzag stitch in elastic materials with a 10-20% short elastic band, pulling the band. Then make 3/16″-1/4″ short inseam.

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Czochralski법에 의한 ZnWO4 단결정 성장 및 특성분석 (Single crystal growth of ZnWO4 by the Czochralski method and characterization)

  • 임창성
    • 분석과학
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    • 제23권2호
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    • pp.103-108
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    • 2010
  • Czochralski법에 의한 $ZnWO_4$ 단결정을 [100], [010], [001] 방향으로 성공적으로 성장시켰다. $ZnWO_4$ 단결정 성장을 위한 종자결정은 백금 침을 사용하여 용융액으로부터 모세관 현상을 응용한 결정성장으로 얻을 수 있었다. 각 축 방향에 따른 성장조건이 rotation speed, pulling rate, 성장된 결정의 직경등의 변수를 가지고 조사되어졌다. 성장된 결정의 냉각시 발생되는 균열을 annealing 효과에 의하여 방지할 수 있었다. 성장된 결정의 방위는 Laue back reflection으로 결정하였다. 각 축 방향으로 성장된 결정의 미세구조적 특징이 논하여졌으며, 경도, 열팽창계수 및 유전상수의 물리적 특성이 평가되어졌다.

An estimation method of full scale performance for pulling type podded propellers

  • Park, Hyoung-Gil;Choi, Jung-Kyu;Kim, Hyoung-Tae
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제6권4호
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    • pp.965-980
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    • 2014
  • This paper presents a new estimation method of full scale propulsive performance for the pulling type podded propeller. In order to estimate the drag of pod housing, a drag velocity ratio, which includes the effects of podded propeller loading and Reynolds number, is presented and evaluated through the comparison of model test and numerical analysis. By separating the thrust of propeller blade and the drag of pod housing, extrapolation method of pod housing drag to full scale is deduced, and correction method of propeller blade thrust and torque to full scale is presented. This study utilized the drag coefficient ratio of the pod housing as a measure for expanding it to full scale, but in order to increase the accuracy of performance evaluation, additional study is necessary on the method for the full scale expansion via separating the drag of pod body, strut and fin which consist the pod housing.

대구경 규소 Czochralski 단결정 속의 결정 결함 규명 (Characterization of the grown - in defects in the large diameter silicon crystal grown by Czochralski method)

  • 이보영;김영관
    • 한국결정성장학회지
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    • 제6권1호
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    • pp.11-18
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    • 1996
  • Czochralski법으로 성장된 대구경(8인치 이상) 규소 단결정속에 폰재하는 결정 결 함을 규명하였다. Ring형 산화 적충 결함(Oxidation Induced Stacking Faults, 일명 OISF)의 발생 형태를 조사하였다. Minority life time을 mappmg하여 본 결과, rmg형 OISF의 폰재는 재료의 전기적 성질에 영향을 미칠 가능성이 높은 것으로 확인되었다. OISF의 핵 생성에 미치는 냉각 속도의 영향을 조사한 결과 homogeneous적 핵 생성 및 성장 현상을 확인할 수 있었다. 또한 COP(Crystal Originated Particle)의 주원인인 FPD(Flow Pattern Defects)의 발생은 용 체의 응고 속도에 크게 화우됨을 발견하였다. 이들 결함의 상반된 발생 현상의 제어를 위하여 는 인상 속도는 느리게, 또한 $950^{\circ}C$ 근처에서의 냉각속도는 빠르게 하는 것이 바람직한 것으로 결함 발생 제어 모델이 제시되었다.

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