• Title/Summary/Keyword: Opening Pressure

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An Investigation into the Effect of Each Parameter on the Damping Forces Using Dynamic Behaviour Analysis P/G of S/A (충격 흡수기의 동적거동 해석 프로그램을 이용한 각 파라미터가 감쇠력에 미치는 영향 조사)

  • Park, J.W.;Shin, S.Y.;Lee, S.B.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.10
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    • pp.44-49
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    • 1997
  • The damping force is determined by four valves and the components which consist of the shock absorber for vehicle. In this study it is investigated the individual effects of four valves and these components on damping forces using dynamic behaviour analysis program of the shock absorber. In addition, opening of main valves are researched during compression and tension cycle due to up- down reciprocation movement of piston. We are to strictly control the properties and tolerance of componenets having important effects on the damping force. Thus we are intended to produce shock absorber of better quality.

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Features and Cost Reduction Effect of High Pressure LNG Pipeline Network (고압 LNG 배관망의 특성 및 비용절감 효과)

  • Kim, Ho-Yeon;Hong, Young-Soo;Noh, Joo-Young;Eom, Yun-Seong;Kim, Cheol-Man
    • Journal of Energy Engineering
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    • v.17 no.3
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    • pp.139-144
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    • 2008
  • Recently due to march as the high oil price, It is necessary for Korea to grope a plan, which is to increase the energy efficiency of existing facilities as well as to develop overseas gas and oil resources. With this point, this work carried out to approach the high pressure LNG pipeline network of Inchon receiving terminal with Newton method as corrective flowrate. We found that the high pressure network mainly depends on FCVs(Flow Control Valves). The high pressure pump showed the maximum efficiency at the FCVs of 50% opening and could discharge LNG only above the LNG head of 1,500m from a system curve obtained. The operating cost of pumps was estimated from their operating points. We compared the operating cost under normal operation with the operating cost under maximum efficiency. Especially, we obtained the day savings of a year as wells as the hour savings of a day. From the results, the high pressure network win be able to reduce the operating cost of 138 million wons in a year. This means that a pump can reduce the operating cost of 9,823 thousands won. Consequently, this work could find the operating features of the pumps under the complicated high pressure LNG network and the savings effect of the pump operating cost. Also, the results will be able to macroscopically contribute the heightening of national energy competitiveness as well as to microscopically contribute the future effective operation of LNG receiving terminal.

Analyses of Plantar Foot Pressure and Static Balance According to the Type of Insole in the Elderly

  • Bae, Kang-Ho;Shin, Jin-Hyung;Lee, Joong-Sook;Yang, Jeong-Ok;Lee, Bom-Jin;Park, Seung-Bum
    • Korean Journal of Applied Biomechanics
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    • v.26 no.1
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    • pp.115-126
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    • 2016
  • Objective: The purpose of this study was to investigate plantar foot pressure and static balance according to the type of insole in the elderly. Methods: Thirteen elderly (mean age: $67.08{\pm}2.25years$, mean height: $159.63{\pm}9.64cm$, mean body weight: $61.48{\pm}9.06kg$) who had no previous injury experience in the lower limbs and a normal gait pattern participated in this study. Three models of insoles of the normal, 3D, and triangle types were selected for the test. The Pedar-X system and Pedar-X insoles, 3.3 km/h of walking speed, and a compilation of 20 steps walking stages were used to analyze foot-pressure distribution. Static balance test was conducted using Gaitview AFA-50, and balance (opening eyes, closing eyes) was inspected for 20 s. One-way ANOVA was conducted to test the significance of the results with the three insoles. p-value of less than .05 was considered statistically significant. Results: The mean foot pressure under the forefoot regions was the lowest with the 3D insole during treadmill walking (p<.05). The mean value under the midfoot was the highest with the 3D insole (left: p<.05, right: p<.01). The mean value under the rearfoot was the lowest with the 3D insole (p<.001). The maximum foot pressure value under the foot regions was the lowest on both sides of the forefoot with the 3D insole. A statistically significant difference was seen only in the left foot (p<.01). The maximum value under the midfoot was the highest with the 3D insole (p<.001). No statistically significant difference was detected on the values under the rearfoot. In the case of vertical ground reaction force (GRF), statistically significant difference was seen only in the left side rearfoot (p<.01). However, static balance values (ENV, REC, RMS, Total Length, Sway velocity, and Length/ENV) did not show significant differences by the type of insole. Conclusion: These results show that functional insoles can decrease plantar pressure and GRF under the forefoot and rearfoot. Moreover, functional insoles can dislodge the overload of the rearfoot and forefoot to the midfoot. However, functional insoles do not affect the static balance in the elderly.

Limit Loads for Circular Wall-Thinned Feeder Pipes Considering Bend Angle (굽힘각도를 고려한 원형 감육이 발생한 중수로 피더관의 한계하중)

  • Bae, Kyung-Dong;Je, Jin-Ho;Kim, Jong-Sung;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.3
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    • pp.313-318
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    • 2012
  • In CANDU, feeder pipes supply heavy water to pressure tube and steam generator. Under service conditions, Flow-Accelerated Corrosion (FAC) produces local wall-thinning in the feeder pipes. The wall-thinning in these pipes affects the integrity of the piping system, as verified in previous research. This paper provides limit loads for wallthinned feeder pipes with $45^{\circ}$ and $60^{\circ}$ bend angles, and proposes an equation that predicts the limit loads for wallthinned feeder pipes with arbitrary bend angles. On the basis of finite element limit analyses, limit loads are obtained for wall-thinned feeder pipes under in-plane bending and internal pressure. There are two cases of in-plane bending: the in-plane closing direction and the in-plane opening direction. The material is considered the effect of the large deformation, so an elastic-perfectly-plastic material is assumed in the calculations.

Assessment of the Internal Pressure Fragility of the CANDU Type Containment Buildings using Nonlinear Finite Element Analysis (비선형 유한요소해석을 이용한 CANDU형 격납건물의 내압취약도 평가)

  • Hahm, Dae-Gi;Choi, In-Kil;Lee, Hong-Pyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.4
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    • pp.445-452
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    • 2010
  • In this paper an assessment of the internal pressure fragility of the CANDU type containment buildings is performed. The uncertainties of the performance of the containment buildings, material properties and tendon characteristics are referred from the in-service reports of Wolsung Unit 1. The containment buildings are modeled as a three-dimensional finite elements with considering the major opening and penetrations. A new method to evaluate the probabilistic fragility of the massive structural system is developed. The fragility curves of the target containment building are presented with repect to the failure modes and reliability levels. The center of wall is reveled as the most weak structural component of the containment building in the sense of the rupture and catastrophic rupture failure modes.

A Study of Stress Ratio Influence on the Fatigue Crack Growth Characteristics of Pressure Vessel Steel at Low Temperature (압력용기용 강의 응력비에 따른 저온 피로균열 진전특성에 관한 연구)

  • 박경동;하경준;박형동
    • Journal of Ocean Engineering and Technology
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    • v.15 no.3
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    • pp.100-106
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    • 2001
  • In this study, CT specimens were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descent temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN $-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

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The Classification and Investigation of Smart Textile Sensors for Wearable Vital Signs Monitoring (웨어러블 생체신호 모니터링을 위한 스마트텍스타일센서의 분류 및 고찰)

  • Jang, Eunji;Cho, Gilsoo
    • Fashion & Textile Research Journal
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    • v.21 no.6
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    • pp.697-707
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    • 2019
  • This review paper deals with materials, classification, and a current article investigation on smart textile sensors for wearable vital signs monitoring (WVSM). Smart textile sensors can lose electrical conductivity during vital signs monitoring when applying them to clothing. Because they should have to endure severe conditions (bending, folding, and distortion) when wearing. Imparting electrical conductivity for application is a critical consideration when manufacturing smart textile sensors. Smart textile sensors fabricate by utilizing electro-conductive materials such as metals, allotrope of carbon, and intrinsically conductive polymers (ICPs). It classifies as performance level, fabric structure, intrinsic/extrinsic modification, and sensing mechanism. The classification of smart textile sensors by sensing mechanism includes pressure/force sensors, strain sensors, electrodes, optical sensors, biosensors, and temperature/humidity sensors. In the previous study, pressure/force sensors perform well despite the small capacitance changes of 1-2 pF. Strain sensors work reliably at 1 ㏀/cm or lower. Electrodes require an electrical resistance of less than 10 Ω/cm. Optical sensors using plastic optical fibers (POF) coupled with light sources need light in-coupling efficiency values that are over 40%. Biosensors can quantify by wicking rate and/or colorimetry as the reactivity between the bioreceptor and transducer. Temperature/humidity sensors require actuating triggers that show the flap opening of shape memory polymer or with a color-changing time of thermochromic pigment lower than 17 seconds.

A Study on Standards for Pressure Relief Valve Vent Pipes from LPG Storage Tanks (LPG용 압력방출밸브 방출관 설치기준 개선방안)

  • Lee, Jin-Han;Eom, Suk-Hwa;Kim, Lae-Hyun
    • Journal of the Korean Institute of Gas
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    • v.16 no.4
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    • pp.59-64
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    • 2012
  • The dispersion of gas discharged from the vent pipes of pressure relief valves attached LPG (Liquefied Petroleum Gas) storage tank was studied. In general, vent pipes should be positioned so that they discharge vertically upwards in a safe place, and installed so that, in the event of ignition of discharged gas, flame impingement on any vessel, equipment or piping is avoided[1][2]. In Korea, on the other hand, there are various type of the end of vent pipes because there is no rule for discharge directions from the vent pipes. In this paper, we took 4 types of vent directions from the pipes in to account, such as vertically upward, vertically downward, vertically 4-way and horizontally 2-way direction. A software package, FLACS, was adopted to simulate gas dispersion from the vent pipes. We found that vertically downward, vertically 4-way and horizontally 2-way discharge from vent pipes were undesirable to avoid ignition on near ground. Therefore, it was obvious that vertically upward opening of a vent pipe is the best option to discharge in a safe place.

EXPERIMENTS ON THE PERFORMANCE SENSITIVITY OF THE PASSIVE RESIDUAL HEAT REMOVAL SYSTEM OF AN ADVANCED INTEGRAL TYPE REACTOR

  • Park, Hyun-Sik;Choi, Ki-Yong;Choi, Seok;Yi, Sung-Jae;Park, Choon-Kyung;Chung, Moon-Ki
    • Nuclear Engineering and Technology
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    • v.41 no.1
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    • pp.53-62
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    • 2009
  • A set of experiments has been conducted on the performance sensitivity of the passive residual heat removal system (PRHRS) for an advanced integral type reactor, SMART, by using a high temperature and high pressure thermal-hydraulic test facility, the VISTA facility. In this paper the effects of the opening delay of the PRHRS bypass valves and the closing delay of the secondary system isolation valves, and the initial water level and the initial pressure of the compensating tank (CT) are investigated. During the reference test a stable flow occurs in a natural circulation loop that is composed of a steam generator secondary side, a secondary system, and a PRHRS; this is ascertained by a repetition test. When the PRHRS bypass valves are operated 10 seconds later than the secondary system isolation valves, the primary system is not properly cooled. When the secondary system isolation valves are operated 10 or 30 seconds later than the PRHRS bypass valves, the primary system is effectively cooled but the inventory of the PRHRS CT is drained earlier. As the initial water level of the CT is lowered to 16% of the full water level, the water is quickly drained and then nitrogen gas is introduced into the PRHRS, resulting in the deterioration of the PRHRS performance. When the initial pressure of the PRHRS is at 0.1MPa, the natural circulation is not performed properly. When the initial pressures of the PRHRS are 2.5 or 3.5 MPa, they show better performance than did the reference test.

Development of Degassing Valves for Food Packaging using Ring Type Rubber Disk (링타입 고무막을 이용한 식품 포장용 가스배출 밸브(Degassing Valve) 개발)

  • Yu, Ha Kyoung;Lee, Kyungo Ho;Oh, Jae Young
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.20 no.2
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    • pp.35-39
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    • 2014
  • One-way degassing valves are designed to allow pressure to be released from an air-tight package while preventing air from getting back into the package. Air, especially the oxygen ($O_2$) portion of air, can have negative effects on the package contents and its freshness. The most common application of the one-way degassing valve is for fresh roasted coffee. Demands of one-way degassing valves have been increasing with the high growth of global coffee market. In this study, we have developed one-way degassing valves for coffee and food packaging using ring type rubber disk, named SP valve. Its quality and performance was verified with test results to be equal with that of global top maker's product, Goglio valve. SP valves showed 820~1200 Pa of opening pressure, 10~50 Pa of closing pressure, 1.2~1.6 L/ min of flow rate. And, the SP valve applicable to ferment food packaging is expected to contribute to globalize Korean traditional food.

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