• Title/Summary/Keyword: Opening characteristics

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STUDY ON FLOW CHARACTERISTICS FOR PRECISION CONTROL BUTTERFLY VALVE (정밀제어용 버터플라이 밸브의 유동특성에 관한 연구)

  • Park, Song Mook;Choi, Hoon Ki;Yoo, Geun Jong
    • Journal of computational fluids engineering
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    • v.19 no.1
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    • pp.21-26
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    • 2014
  • Butterfly valve is a valve that controls fluid flow depending on the size of the opening angle. In general, the size of the opening angle of the valve increases, the fluid flow has also increased sharply. However, sometimes, in a specific piping system, a particular operating condition is needed that the fluctuation of the fluid flow should not have large amount although the size of opening angle of the valve become larger. In butterfly value, the shape of a typical thin plate, it is impossible to control a minute fluid, but in thick plate type, it is possible. In this study, we got the fluid flow control characteristics and pressure drop through both a numerical method and an experimental method about thick plate type. The numerical result and experimental result of flow coefficient show a similar pattern. In addition, we could find that minute fluid flow control was possible in the area of small size of the opening angle.

Evaluation of Transient Performance of Carburettered Gasoline Engine (과도운전시 가솔린기관의 성능평가)

  • Cho, G.S.;Ryu, J.I.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.3
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    • pp.1-11
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    • 1993
  • An experimental study was carried out to evaluate the characteristics of transient performance of carburettered gasoline engine under rapid accelerating transient driving conditions. In order to evaluate the characteristics of transient performance quantitatively, the concept of dead time $t_d$ response delay time $t_r$ are introduced. Performance parameters such as air mass fiowrate Gat, engine speed N, manifold boost pressure Pb, and output torque T are measured simultaneously during the rapid opening of the throttle valve by the stepping motor. During the rapid opening of the throttle valve, air mass fiowrate Gat is increased immediately without delay time, but response of engine revolution N, and output torque T are delayed. Therefore hesitation, and stumble phenomena are occurred. Dead time $t_d$ and response delay time $t_r$ of engine revolution N, which is extremely delayed comparing to other performance parameters, are respectively 0.2-0.3sec., 3.0-4.6sec., and dead time rate $t_d/{\Delta}t$ and response delay time rate $t_r/{\Delta}t$ are linearly increased with the throttle valve opening rate ${\theta}$ during the acceleration from 12 degree to 20 degree at 1250rpm.

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A Study on Operating Method of Public Information System of Archival Institutions (영구기록물관리기관의 공개제도 운영방안 연구)

  • Yoon, Yeo-Jin;Kim, Soon-Hui
    • Journal of Korean Society of Archives and Records Management
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    • v.9 no.1
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    • pp.51-75
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    • 2009
  • In this study, the improvement plan for the appropriate archives opening system in this country was proposed, by searching for the optimal operating method of opening system of archival institutions through the foreign instances related to the integrated type operation and the separate type operation. The opening system in the archival institutions shall be operated in consideration of the characteristics of the preserved archives and the various values and contexts rather than riding on the administrative logics. The opening system in the archival institutions shall be operated in consideration of the characteristics of the preserved archives and the various values and contexts rather than riding on the administrative logics.

Types and Trade Characteristics of Clothes Imported from Japan during the Port-Opening Era (개항기 일본으로부터 수입된 의복의 종류와 무역 특성)

  • Kim, Soon-Young
    • Journal of the Korean Society of Clothing and Textiles
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    • v.46 no.5
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    • pp.890-909
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    • 2022
  • This study explores the types of clothing imported from Japan during the port-opening era and investigates the characteristics of import trade related to these clothing products. This is a literature study based on trade statistics data and books on Western clothing published in Japan during the Meiji period. Research findings are as follows: clothing products imported from Japan were divided into 6 types: 1) clothing, 2) undergarments, 3) shirts, 4) waterproof coats, 5) European-style clothing, and 6) nightgowns. "Clothing" is a unified name for any kind of garment, appearing in import records only from 1877 to 1884. Undergarments and shirts were imported from 1884. Waterproof coats were imported only in 1886 and 1898. European-style clothing and nightgowns were imported from 1902. In the total import of clothes, the proportion of clothing was the highest (48.0%), followed by undergarments (41.3%) and shirts (10.6%), while the ratio of nightgowns and raincoats was almost 0%. During the port-opening period, the change in the import value of clothes did not show a continuous increase, but rather showed a large stepwise increase over the course of several years.

Experimental Study for the Development of New Type Water Ejector (신형 수이젝터 개발을 위한 실험연구)

  • Mun, Soo-Bum;Choi, Hyun-Kue;Choi, Jae-Hyuk;Kwon, Hyung-Jung;Kim, Kyung-Keun;Choi, Soon-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.6
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    • pp.677-684
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    • 2006
  • An ejector is a fluid transfer device to be used for mixing of fluids, maintaining vacuum, and overcoming a poor suction condition. To date, most ejectors have been made from the casting process. which is time-consuming and high-cost process. Therefore, a new production method of ejectors is desired if any. In this experimental study, we proposed a new type ejector manufactured from the commercial fitting materials and the welding process, which is equipped with an orifice type nozzle. The proposed ejector has a good integrity compared with the conventional ejector because the fittings have manufactured by forging and they have more strength than the casting materials. Furthermore we adopted a multi-opening orifice type nozzle for improving a suction capacity and compared with a single-opening orifice type nozzle. From the experimental results. we confirmed that the multi-opening nozzle had a food suction capacity than the single-opening nozzle and the proposed new type ejector showed higher vacuum than the conventional type ejector in non-load condition. These improved characteristics suggests that a new type ejector by using the commercial fittings opens the feasibility to be adopted in various industry fields and that the increased suction capacity can be achieved by altering the nozzle design of a conventional ejector.

A Study on the Characteristics of Natural Convection in a Partially Opened Enclosure with a Heat Source (발열체와 부분 열림 수직벽을 갖는 사각 공간 내 자연대류 특성 해석)

  • Sim, Dong-Sik;Gang, Bo-Seon;Cha, Dong-Jin;Ju, Won-Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.12
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    • pp.1588-1595
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    • 2000
  • Natural convection heat transfer in an enclosure with an opening in the right veritcal wall and a heat source at the bottom surface is investigated using a holographic interferometric technique. The effects of the opening length, divider length attached to the top wall, and heater temperature on the temperature distribution are examined. The opening length as well as the divider length greatly affects the degree of inflow and outflow of air. In the case of small opening length, the opening doesnt affect much the upward warm air flow resulting in the symmetric temperature distribution .The upward flow in hindered by the divider resulting in the decrease of heat transfer from the heater region to the upper region. The longest divider shows the highest temperature in the lower region of enclosure. In the case of large opening length, the inward cold flow moves the upward flow to the left direction. Among the cases of different divider length, the case of H(sub)d=0.25H shows the highest temperature in the lower region of enclosure.

Structural Performance of Reinforced Concrete Shear Walls Partially Cutted for Opening (개구부 설치를 위해 인위적 손상을 가한 전단벽의 구조성능 평가)

  • Choi, Youn Cheul;Choi, Hyun Ki;Choi, Chang Sik;Lee, Li Hyung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.3
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    • pp.77-86
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    • 2007
  • The more demands on efficient utilization of resources, the more structural engineers prefer to select remodeling to improve old building's capacity. A series of four shear wall specimens were tested under constant axial stress and reversed cyclic lateral loading in order to evaluate the effect of the opening on the lower center of the wall induce by remodeling. Consequently, the existence of opening was verified to induce a different failure, which was caused by reduction of compression strut area formed on the wall to diagonal direction. Especially, the ultimate strength of the wall with an opening was revealed approximately 35% lower than that of the wall without an opening. And the similar results were appeared in characteristics of stiffness and energy dissipation capacity.

Wind tunnel study on fluctuating internal pressure of open building induced by tangential flow

  • Chen, Sheng;Huang, Peng;Flay, Richard G.J.
    • Wind and Structures
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    • v.32 no.2
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    • pp.105-114
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    • 2021
  • This paper describes a wind tunnel test on a 1:25 scale model of TTU building with several adjustable openings in order to comprehensively study the characteristics of fluctuating internal pressures, especially the phenomenon of the increase in fluctuating internal pressures induced by tangential flow over building openings and the mechanism causing that. The effects of several factors, such as wind angle, turbulence intensity, opening location, opening size, opening shape and background porosity on the fluctuating internal pressures at oblique wind angles are also described. It has been found that there is a large increase in the fluctuating internal pressures at certain oblique wind angles (typically around 60° to 80°). These fluctuations are greater than those produced by the flow normal to the opening when the turbulence intensity is low. It is demonstrated that the internal pressure resonances induced by the external pressure fluctuations emanating from flapping shear layers on the sidewall downstream of the windward corner are responsible for the increase in the fluctuating internal pressures. Furthermore, the test results show that apart from the opening shape, all the other factors influence the fluctuating internal pressures and the internal pressure resonances at oblique wind angles to varying degrees.

Effects of Initial Condition and Opening Geometry of a Compartment on the Gravity Current in the Backdraft (백드래프트의 중력흐름에 미치는 구획실 내부 초기조건 및 개구부 형상의 영향)

  • Park, Ji-Woong;Oh, Chang Bo;Han, Yong Shik;Do, Kyu Hyung
    • Journal of the Korean Society of Safety
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    • v.30 no.6
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    • pp.18-25
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    • 2015
  • Computational study of a gravity current prior to the backdraft was conducted using fire dynamic simulator (FDS). Various initial conditions of mixture compositions and compartment temperature as well as four opening geometries (Horizontal, Door, Vertical, and Full opening) were considered to figure out their effects on the gravity current. The density difference ratio (${\beta}$) between inside and outside of compartment, the gravity current time ($t_{grav}$) and velocity ($v_{grav}$), and non-dimensional velocity ($v^*$) were introduced to quantify the flow characteristics of the gravity current. Overall fluid structure of the gravity current at the fixed opening geometry showed similar development process for different ${\beta}$ conditions. However, $t_{grav}$ for entering air to reach the opposed wall to the opening geometry increased with ${\beta}$. Door, Vertical, and Horizontal openings where openings are attached on the ground showed similar development process of the gravity current except for Horizontal opening, which located on the middle of the opening wall. The magnitude of $v_{grav}$ at fixed ${\beta}$ was, from largest to smallest, Full > Vertical > Door > Horizontal, but it depended on both the size and location of the opening. On the other hand, $v^*$ was found to be independent to ${\beta}$, and only depended on the geometry of the opening.

Effect of Opening Pressure and Ambient Pressure on the Characteristics of Atomization in Early Stage of Diesel Spray (개변압 및 배압 변화가 디젤부문의 초기 미립화 특성에 미치는 영향)

  • 김종현;이봉수;이장희;구자예
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.56-62
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    • 1999
  • The disintegration of transient diesel spray in early was investigated at different opening pressure and chamber pressure by measns of shadowgraph method using nanolite and still camera. Diesel spary was injected into the spray chamber which was charged with high pressure nitrogen gas. Atthe begining of injection, a liquid column that was almost the same diameter as the nozzle hole was observed . Spray tip penetration and spray angle were always increased with an increase in opening pressure.

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