• 한국전산유체공학회지
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• 제19권1호
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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.

• 한국자동차공학회논문집
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• 제1권3호
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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.

• 한국기록관리학회지
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• 제9권1호
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• pp.51-75
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• 2009

공공기관에서 생산된 기록물이 제대로 활용하기 위해서는 기록물 공개가 우선되어야 한다. 어떤 기록물이 어떤 시점에 공개되어야 하는지를 판단하는 것은 매우 까다롭고, 무엇보다 이러한 판단에는 다양한 이해관계가 얽혀 있기 때문에 관련 규정과 운영현황을 재검토해 볼 필요가 있다. 이를 위해 본 연구에서는 기록물 활용단계별 공개제도의 특성을 토대로 현재 운영하고 있는 공개제도의 문제점을 살펴보고, 국내외 공개제도 분석을 통해 보다 전문적으로 효율적인 서비스 제공을 위한 우리나라 공개제도 운영 개선방안을 제안하였다. 특히 통합형 공개제도 운용과 분리형 공개제도 운영의 장단점 분석을 통해 우리나라에 적합한 공개제도 운영모델을 구상하는 데 초점을 두었다.

• 한국의류학회지
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• 제46권5호
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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.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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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.

• 대한기계학회논문집B
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• 제24권12호
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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.

• 한국구조물진단유지관리공학회 논문집
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• 제11권3호
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• pp.77-86
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• 2007

건축물의 증가와 자원의 효율적인 활용의 목적으로 기존 건축물에 대한 리모델링이 주목을 받고 있다. 리모델링 공사로 인해 세대간 병합을 위해 기존 벽에 개구부를 설치하는 경우 개구부의 영향을 파악 하는 것을 목적으로 철근콘크리트 전단벽의 정적가력 실험을 실시했다. 그 결과 개구부 유무에 따른 파괴현상은 벽판에 형성된 압축지주의 단면적이 감소함으로써 다르게 나타났다. 특히 최대 내력은 개구부 설치에 따라 약 35%정도 감소되는 특성을 보였다. 이러한 경향은 강성 및 에너지 소산능력에서도 유사하게 나타났다.

• Wind and Structures
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• 제32권2호
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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.

• 한국안전학회지
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• 제30권6호
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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.

• 한국자동차공학회논문집
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• 제7권9호
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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.