• 제목/요약/키워드: Back-pressure rise

검색결과 31건 처리시간 0.023초

인체의 동작을 고려한 스케이트 팬츠 패턴 개발 (Pattern Development of Skate Pants Allowing for Dynamic Movement and Postures)

  • 정연희
    • 한국생활과학회지
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    • 제17권1호
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    • pp.115-126
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    • 2008
  • The construction of an athlete's tight-fitting garments is very important to the wearer in terms of athletic performance. Therefore pattern development of tight-fitting garments must allow for the full range of human movement and postures. In this study the relationship between the construction of a skate pants pattern and clothing fitting was explored with the aim of improving the comfort of the clothing. The four male subjects were university students between the ages of 20 to 24. Subjective wear sensations of the experimental garments were rated using a seven-point Likert scale on four consecutive days. While wearing the garments, subjects were asked to take five different postures including waist flexion, sitting and others. A Likert-type scale was used for the evaluation, with 7 points indicating the best fit in tight-fitting pants. Results showed differences in the front-rise length and back-rise length between basic pants(A) and modified pants(B,C,D) were -5.16cm and +5.64cm. Comparing the basic pants pattern(A) with modified pants pattern(B), the latter was superior to basic pants(A) in terms of pressure sensation and closeness of fit, but there was no significant difference. Among the four tight-fitting skate pants, A and B pants were superior to the others in terms of fitting and stability of waist and hip sections. In the case of the skate pants, the number of cutting lines in the pattern had an influence on clothing comfort. A minimum cutting line for tight skate pants was better than a maximum cutting line in terms of clothing comfort.

소형 축류홴의 난류유동 특성치에 대한 LDA 측정 (LDA Measurements on the Turbulent Flow Characteristics of a Small-Sized Axial Fan)

  • 김장권
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.371-376
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    • 2001
  • The operating point of a small-sized axial fan for refrigerator is strongly dependent upon the system resistance. Therefore, the turbulent flow characteristics around a small-sized axial fan may change significantly according to the operating point. This study represents three-dimensional turbulent flow characteristics around a small-sized axial fan measured at the four operating points such as $\varphi=0.1$, 0.18, 0.25 and 0.32 by using fiber-optic type LDA system. This LDA system is composed of a 5 W Argon-ion laser, two optics in back-scatter mode, three BSA's, a PC, and a three-dimensional automatic traversing system. A kind of paraffin fluid is utilized for supplying particles by means of fog generator. Mean velocity profiles downstream of a small-sized axial fan along the radial distance show that both the streamwise and the tangential components exist predominantly in downstream except $\varphi=0.1$ and have a maximum value at the radial distance ratio of about 0.8, but the radial component, which its velocity is relatively small, is acting role that only turns flow direction to the outside or the central part of axial fan. Moreover, all of the velocity components downstream at $\varphi=0.1$ show much smaller than those upstream due to the static pressure rise at the low-flowrate region.

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프로펠러 압력면 캐비테이션의 초기발생 추정 및 실험 검증 (Prediction of the Propeller Face Cavity Inception and Experimental Verification)

  • 안병권;이창섭;유용완;문일성
    • 대한조선학회논문집
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    • 제44권5호
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    • pp.467-473
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    • 2007
  • Cavitation phenomena appearing on ship propellers have long been interested and recent theoretical analysises give good results comparing with model tests. In accordance with a continuous rise in heavy powered and high speed ships, hull forms have been changed and loads acting on the propeller surface have also been increased, and they result in various and particular cavitations. In some cases, cavitation appears not only on the back but also on the face of the propeller and it causes additive pressure fluctuations and erosion of the propeller and reduces propulsion efficiency of the ship. In this study, we predict the face cavity inception using unsteady propeller analysis based on the panel method and compare the results with experimental observations.

수중로봇용 AC구동시스템의 속도센서 제거를 위한 속도추정법 연구 (An Approach to a Speed Estimation Method to Remove Speed Sensor of Underwater Robot's AC Drive Systems)

  • 전봉환;임용곤;이판묵
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 1998년도 춘계종합학술대회
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    • pp.371-376
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    • 1998
  • This paper describes an approach to a speed estimation method to remove speed sensor of underwater robot's AC drive systems. AC motors have been widely used in the field of underwater robot's manipulator or propulsion system. Most of these AC motors for underwater use have usually filled oil to compensate the high pressure in deep-sea operation, where a resolver is adopted to feed back the speed of rotor But this kind of speed feedback devices gives rise to some defects arising from their mechanical complexity and numerous signal lines; a resolver needs 6 or 7 signal lines for proper operation. This paper presents a speed estimation method to improve these problems of induction motor, which is adopted as a prototype of AC motor. The proposed speed estimation method is based on the RFO(rotor flux orientation) vector control method of voltage-fed AC drives. Using the controller of voltage-fed AC drives, it is unnecessary to measure the voltage for the estimation of rotor speed, which reduces the effects of measurement error Numerical simulation is carried out to investigate the validity of the method and the effects of rotors resistance variation.

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특별피난계단 부속실 제연설비의 방연풍속 기류특성에 관한 실험적 연구 (Experimental Study on Features of Air Egress Velocity in Vestibule Pressurization System)

  • 류성호;이수경;홍대화;윤명오;최금란;박재현
    • 한국화재소방학회논문지
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    • 제24권5호
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    • pp.79-86
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    • 2010
  • 본 연구는 국내 고층건물 특별피난계단의 부속실에 설치되는 급기가압 제연시스템의 방연 풍속 기류 가화재 발생 시 피난을 위하여 출입문이 개방되었을 경우 거실 방향으로 정상적으로 형성되지 않고 부속실 내부로 역류되는 현상을 개선하기위해 실 모형실험을 통해 출입구 상부로 역류하지 않는 조건을 개발하였다. 부속실 바닥 면적이 $2m^2$$4m^2$인 두개의 실물 모형을 제작하여 실험을 실시한 결과, 방연풍속의 기류 특성은 바닥 면적이 $2m^2$인 경우 심하게 출입문 상부로 기류가 역류되었다. 다만, 급기댐퍼의 설치위치가 출입문 맞은편의 경우 날개각도가 45도 상향인 경우는 출입문 상부로는 역 기류 현상은 없었지만 하부로는 일부 역류 되었다. 부속실 면적이 $4m^2$ 인 경우는 출입문에서 거실방향으로 정상적인 기류 분포를 보였다. 부속실 바닥 면적이 작게 설계될 경우에는 성능위주 설계가 될 수 있도록 하여야 한다.

Design of a Microthruster using Laser-Sustained Solid Propellant Combustion

  • Kakami, Akira;Masaki, Shinichiro;Horisawa, Hideyuki;Tachibana, Takeshi
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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    • pp.605-610
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    • 2004
  • Solid propellants allow thrusters to be light-weight, com-pact and robust because they require neither tank nor valve, Moreover, the solid propellant will not leak, spill or slosh. Consequently, the solid propellant thruster is one of the potential candidates for the microthruster. On the other hand, the control of the solid propellant combustion is difficult, since the conventional solid propellant continues to bum until all the stored propellant is consumed. Although particular devices like thrust reverser were designed to control the combustion, these devices were rarely used in the practical rocket motors. These devices rise thruster weight as well as complicate the thruster operation. In this study, a solid propellant microthruster using laser sustained combustion was designed in order to develop a high-efficiency microthruster overcoming the previously-mentioned difficulty. This designed thruster has semiconductor lasers and non-self-combustible solid propellants in addition to the conventional solid propellant thruster. In this designed thruster, the semiconductor laser controls the combustion of the non-self-combustible solid propellant. In order to demonstrate that the solid propellant combustion is controllable with laser, some non-self-combustible solid propellants were irradiated with the laser at a back-pressure of about 1㎪. A 40-W class Neodymium Yttrium Aluminum Garnet (ND:YAG) laser was used as a tentative alternate to the semiconductor laser. This experiment has shown that the solid propellant combustion was controllable with 10- W class laser irradiation.

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韩国对外战略调整的原因分析-美中战略竞争下不断增加的北韩威胁对东北亚安全局势带来的深远影响 (Analysis of the Reason for ROK's Foreign Strategy Adjustment: The growing threat from DPRK under the U.S.-China strategic competition and its profound influences on the security situation in Northeast Asia)

  • 金东灿;李章源
    • 분석과 대안
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    • 제7권3호
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    • pp.115-144
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    • 2023
  • 特朗普政府时期美国已表明了 "中国是美国的战略竞争者, 也是修正主义势力, 更是对美国繁荣和安全的主要挑战" 这种立场, 拜登政府也基本上继承了这种对中国的认识。中国也对此积极应对。因此, 美中战略竞争已成为当今国际体系中最重要的背景因素, 也对东北亚安全局势产生了巨大的影响。尽管如此, 观察最近韩美日三边安全合作的形成过程时我们可以发现, 尹锡悦总统上台之后韩国的对外战略调整对韩美日三边安全合作的形成起到了关键性作用。这是因为美国一如既往希望构建的韩美日三边安全合作的成败取决于韩日关系的改善, 而尹锡悦政府不顾韩国国内政治的制约因素, 果断推动了韩日关系的快速改善。随后, 在戴维营召开的韩美日三国峰会为未来三国在安全及其他更广泛领域的合作奠定了基础。中国对韩美日三边安全合作的形成提出了强烈的不满和抗议。但本文认为, 韩国虽然同意与美国和日本形成韩美日三边安全合作, 但韩国的战略目标与美国和日本的战略目标都不完全一致。比如, 回顾冷战结束之后的美日同盟发展历程, 美国与日本都对中国的崛起持有类似的看法和认识。最近几年美日同盟加强的实际目标也主要是如何应对中国的崛起。与此相反, 韩国历届政府都对韩美日三边安全合作持消极的态度。这是因为韩国想要追求的最主要的战略目标是如何减少或消除来自北韩的威胁, 而不是应对中国。面对北韩不断增强的挑衅与威胁, 过半数的韩国人支持通过加强韩美日三边安全合作来遏制或缓解来自北韩的威胁。因此, 只要北韩的核威胁与导弹挑衅持续存在, 那韩国的对外战略方向就很可能是加强韩美日三边安全合作, 以确保自身的安全与生存。所以, 如果中国想要减少韩美日三边安全合作给中国带来的战略上的压力, 最好的方案是降低北韩对韩国的挑衅和威胁, 在让北韩放弃核武器的问题上扮演更加实质性的角色。

저수위 변동에 영향을 받는 강기슭의 산사태 해석 II (Landslide Analysis of River Bank Affected by Water Level Fluctuation II)

  • 김유성;왕 유메이;최재선
    • 한국지반신소재학회논문집
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    • 제9권3호
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    • pp.87-93
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    • 2010
  • 저수지의 수위변화는 저수지 주변 강기슭 사면파괴의 주요 요인이다. 중국의 삼협댐 저수위는 홍수량 조절을 위해 145m와 175m사이에서 변화한다. 삼협댐 저수위의 정상적 운영상태에서 저수위 변동속도는 0.67m~3.0m의 범위에 있다. 마지아고 사면은 자시강의 2.1km 상류 좌측기슭에 위치한다. 자시강은 삼협지역내에 있는 양츠강의 지류이다. 2003년 저수위가 95m에서 135m로 상승한 직후, 마지아고 사면의 후면부에서 길이 20m, 폭 3~10의 균열이 발생하였다. 지금은 균열 보수 후 특별한 징후는 보이지 않고는 있으나, 이 큰 균열은 마지아고 사면의 산사태 가능성을 암시하고 있었다. 이 연구에서는 침투해석에서 얻어진 간극수압을 저수위 변동에 따른 안전율 변화를 평가하기 위해 사용되었다. 안전율 평가는 한계평형해석에 의한 사면안정해석에 의해 수행되었다. 한계평형해석에서 전단강도에 미치는 부의 간극수압 효과는 불포화 흙에 대한 프레드런드의 전단강도식을 사용하여 고려하였다. 연구결과 강기슭사면의 안전율은 저수위의 상승, 하강에 따라 감소와 증가의 경향을 보이나, 가장 위험한 상태는 저수위가 최대높이를 장기간 유지할 때인 것으로 나타났다.

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두개내압상승(頭蓋內壓上昇)과 궐의(厥) 상관성(相關性)에 대(對)한 동서의학적(東西醫學的) 고찰(考察) (The Eastern and Western Medical Investigation on the Relation with I.I.C.P and Kwul)

  • 정승현;박성식;이원철
    • 동국한의학연구소논문집
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    • 제3권
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    • pp.237-267
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    • 1994
  • The purpose of this study is the approach to I.I.C.P. centered on the meaning of consciousness disorder and the pathological aspect of Kwul (Jose consciousness ; faint, fall into a coma). The meaning of consciousness disorder and apoplexy is evidently involved the definition of Kwul. 1. It is found that the etymological interpretation on Kwul which the energy rises back to go through blocked space and the meaning interpretation of regarding Kwul as apoplexy with medical viewpoint, are related with consciousness disorder and motor disturbance in IICP in the aspect of the rise of Kwul and the abnormal rising of vital energy and blood, In addtion, the overall of meaning of Kwul is showed in table <1-1> by reference to doctors of many generations, 2. The pathology of Kwul includes abnormal rising, sthenia-syndrome in the upper part and asthenia in the lower, the origin of Kwul, the lower, looking like Yin by too sthenic Yang and looking like Yang by too sthenic Yin. The headache, vomiting, papilledema, paralysis of nervi craniales, coma, blood pressure rising, tachycardia by I.I.C.P can be regarded as a conception of trouble of vital energy, sthenia-syndrome of Kwul. The pulse pressure, brachycardia, bradypnea can be regarded as the conception of looking like Yin by too sthenic Yang. 3. In the emergency of Kwul, the abnormal ternimal reversion of the Kwulyin channel, Kuyang channel, and three Yins are related with the phenomenon in I.I.C.P. It is considered that the reverse movement of materials, I.I.C.P. can be closely observed by giving meaning on the meridian of Kwul in Somunkwulron. And the content of phrases of Naelyung which includes consciousness disorder refered in the chapter of Kwul, is compared with I.I.C.P. 4. The followings should be considered; examination of optic symptom and abnormal posture in cerebral herniation ; understanding and working out counterplans of factors and symptoms of consciousness disorder by the observation of vital sign, check of general stages, neurologic inverstigation, clinical diagnosis, and subsidiary diagnosis; application of morphological change of opinion; addtion of the conception of demonstration centered on Yunkyung, Samyinkwulruk, asthenia and thenia of healthy energy in oriental medicine. 5. The similarity of Kwul and I.I.C.P. can be found from etiology and pathotenic factor. The similarity is clearly found by investigation of etiology, pathotenic factor, symptoms and thrapy of Kwul, disease symptom ar.d other symptoms.

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이암 절취사면의 붕괴이력을 고려한 강우침투에 따른 안정성 분석 (The Effect of Rainfall on the Stability of Mudstone Slope in Consideration of Collapse Record)

  • 전병추;이수곤;김영묵;정성래
    • 한국지반공학회논문집
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    • 제25권2호
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    • pp.55-66
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    • 2009
  • 경상북도 포항시 동해면 석리지역의 국도변에 위치한 이암으로 구성된 사면에서 실제로 발생한 사면붕괴 사례를 중심으로 이암사면의 강우유형에 따른 침투해석을 시행하여 강우가 사면에 미치는 안정성 분석에 대한 연구를 수행하였다. 이를 위하여 붕괴가 발생한 사면을 대상으로 정밀지표조사, 지구물리탐사 및 시추조사를 수행한 후 상세 지층상태를 분석하고, 붕괴 활동면이 위치하는 구간에 대하여 slaking/swelling시험을 통해 내구성이 저하되는 것을 파악하고, 현장투수시험을 통해 토층별 투수성을 파악하였다. 또한 한계평형해석 프로그램인 Talren 97을 이용하여 역해석에 의한 강도정수의 변화분석 및 Slope/W 프로그램을 이용하여 호우시 침투거동과 강우량에 따른 사면내 수압의 변화에 의한 불안정하게 되는 과정을 분석하였다. 실제 붕괴이력을 갖는 사면을 대상으로 지형적인 조건과 서로 상이한 강우조건을 적용하여 사면의 지질구조대 발달 및 사면표면의 상태에 따른 강우침투로 인한 지하수의 상승과 강우지속시간에 따른 침투해석을 통해 사면의 안정성을 분석하였다.