• 해양환경안전학회지
• /
• 제21권3호
• /
• pp.309-314
• /
• 2015

A sunken ship often involves an oil spill. This paper was carried out to minimize environmental and cost damages stemming from oil spil of sunken shipl. Through the analysis of both the standards of the oil tank system and installation, we have identified potential oil spill sites and proposed a remedy of prevention. The result of study, the air pipes of the oil tank are a vulnerable point for oil spill. Also, the remote control devices of emergency shut-off valve have poor accessibility at abandon ship, making it difficult to shut off the emergency shut-off valve. Thus, we propose the addition of a remote quick closing valve in the air pipe and the building of a central control system.

• 해양환경안전학회지
• /
• 제15권3호
• /
• pp.251-256
• /
• 2009

이 연구에서는 전 유동장의 순간속도를 계측 할 수 있는 PIV계측기법을 슬라이딩 밸브의 폐쇄 직후에 적용하고 짧은 시간에 발생하는 디스크 주위의 비정상 속도를 계측하여 유동특성을 실험적으로 고찰하였다. 순간유동장을 분석한 결과를 기존의 압력변동을 측정한 연구 결과에 비교 검토한 결과 슬라이드 밸브 급폐쇄에 따른 속도변동이 크게 나타나는 시간구간은 0.1초 이내이고 주기는 0.12초로 추정되었다. 또한 원관 내부의 디스크 주위유동은 상부부터 폐쇄되면서 유로가 좁아져 순간적으로 빠르게 하류로 진행하였으며 폐쇄직후에 역류하는 속도의 크기는 4/120초까지 감소하다가 다시 증가하는 경향을 보였다. 그리고 완전 폐쇄 후 상류 측으로 역류하는 흐름의 영향으로 y/D=0.2 하부 영역에 역류하는 속도성분이 나타났으며, y/D=0.7, x/D=-0.3의 근방에서 0.2D 크기의 회전와류가 관찰되었다.

• 한국가시화정보학회지
• /
• 제15권1호
• /
• pp.11-18
• /
• 2017

A two-phase flow observed in a heat exchanger or nuclear power generation often has a profound effect on undesirable noise or flow characteristics. Void fraction, which refers to the ratio of gas (or liquid) to the total fluid, affects heat transfer coefficient, vibration and so forth. In other words, void fraction is one of most important parameters in two-phase flow since it contributes to comprehend the characteristics of two-phase flow. We developed a two-phase flow visualization system to measure cross-sectional and volumetric void fractions by using quick closing valves and image processing software. With this system, we could observe the plug, slug, and stratified flow patterns of two-phase flow and measure a myriad of void fractions. As a consequence of the experiment, we found that the estimated void fractions were largely coincident with the predictive values by Chisholm model.

• 대한한의학원전학회지
• /
• 제13권1호
• /
• pp.74-101
• /
• 2000

Geungyul(根結) means roots and nodes of meridians. If human body gets damaged by energy which each seasons has, the meridians get some troubles. Healing for symptom, meridians consist of root, stay, follow, inpouring and node of acupuncture points should be in harmony. 1. This chapter explain roots and node parts of each meridian, acupuncture points name and root, stay, follow, inpouring of acupuncture points which in arm and leg of three Yin and Yang. 2. The opening, closing, axis function, the symptom, and the needling of both meridians of Yin and Yang are explained. 3. The method that predicts the rise-and-fall of visceral energy and the time of death by using an order of pulse and intermittent pulse is explained. 4. It is explained that since the physical condition of the rich and the poor are different, the method using a needling for each person to be healed, such as the deep-and-shallow and the quick-and-slow, are different. 5. It is explained that the excess and the deficiency in the energy of shape should be considered when a acupuncture is given.

• 대한기계학회논문집
• /
• 제18권9호
• /
• pp.2251-2256
• /
• 1994

An experimental study was conducted on water hammer phenomena generated by quick valve operations in piping systems of buildings. Transient water hammer pressure waves were measured for three different types of valves, i. e. a ball valve, a solenoid valve, and on one-touch valve. The effects of flow rate and valve closing time on the maximum water hammer pressure were investigated. Based on the experimental results, general design recommendations were provided to prevent water hammer phenomena in piping systems of high-rise apartment buildings.

• 설비공학논문집
• /
• 제12권7호
• /
• pp.697-702
• /
• 2000

This study is to investigate the pressure wave characteristics and the maximum pressure rise generated by instantaneous valve closure at the end of the straightening copper piping system. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s and water temperature $20^{\circ}C$ . Results indicated that the peak pressure generated by quick valve closure reached Joukowsky's value. And we also found that the maximum pressure rise and the pressure history were depended on not only closing time but also flow velocity.

• Journal of Magnetics
• /
• 제18권4호
• /
• pp.466-472
• /
• 2013

This paper presents a new design of the hybrid magnet engine valve actuator using the shorted turn for enhanced dynamic performance. The quick response of coil electric current is the most important factor that determines the opening and closing performance of the hybrid magnet engine valve. The conventional hybrid magnet engine valve actuator, however, has a delayed initial electric current rising when it is driven by voltage control because of the coil inductance which is a typical characteristic of an electromagnetic coil. A shorted turn is newly placed into the upper yoke of the hybrid magnet engine valve actuator to reduce coil inductance and thus, to hasten the initial electric current rising. We performed a dynamic finite element analysis to demonstrate the improvement of the dynamic characteristics of the hybrid magnet engine valve actuator due to the shorted turn.

• 대한인간공학회지
• /
• 제27권3호
• /
• pp.61-69
• /
• 2008

The purpose of this study was to examine the effects of sensibility and compatibility from function sounds of mobile phones. For this purpose, the present study extracted sensibility adjectives and carried out sensibility evaluation to identify the sensibility factors in the function sounds of mobile phones. And 65 sound sources out of six categories were investigated for 27 subjects. The result showed that two dominant sensibility factors were the duration and the melody pattern of the sound sources. The compatibilities of opening and closing sounds were evaluated lowly with short duration and quick tempo. Especially, the most of the subjects preferred more attractive and longer opening sounds than other function sounds. Another finding was that the short sounds with melodies were preferred for cancellations and alerts, unliked the commonly used sound sources in industry and other traditional electronic products.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집E
• /
• pp.229-234
• /
• 2001

An adiabatic counter-current vertical two-phase flow of air and water in narrow rectangular channels with offset strip fm was investigated experimentally. Tests were systematically performed with downward liquid superficial velocities and upward gas velocities covering 0 to 0.06 m/s and 0 to 2.5 m/s ranges, respectively. Two-phase flow regimes were classified by examining the video images of flow patterns in transparent test sections of 760 mm long and 100 mm wide channel with gaps of 3.0 and 5.0 mm. The channel average void fraction was measured by the quick-closing valve method. Unlike the flow regimes in the channels without fin, where bubbly, slug, chum, and annular flow were identified, only bubbly and chum flow regimes were found for the channels with offset strip fin. However the existence of fin in the channels showed negligible effects on the void fraction. Instead counter-current flow limitations were found to happen at lower air superficial velocity once offset strip fin was introduced in narrow rectangular channels.

• 한국자동차공학회논문집
• /
• 제7권9호
• /
• pp.36-47
• /
• 1999

Three-way catalyst converter, cleaning up the exhaust gas contamination of SI engine, has the best efficiency when A/F ratio is near the stoichiometry . The feedback control using oxygen sensors in the exhaust manifold has limits caused by the system delays. So the accurate measurement of air flow rate to an engine is essential to control the fuel injection rate especially on transient condition like the rapid throttle opening and closing. To measure the rapid change of flow rates. the air flow meter for the engine requires quick response, flow reversal detection, and linearity . Tjhe proposed integration type air flow meter (IFM), composed of an ultrasonic flow meter with an integration circuit, has significantly improved the measurement accuracy of air mass inducted through the throttle body. The proposed control method estimated the air mass at the cylinder port using the measured air mass at the throttle . For the fuel dynamic model, the two constant fuel model is introduced . The control parameters from air and fuel dynamics are tuned to minimize the excursion of the air fuel ratio. As a result A/F ratio excursion can be reduced within 5% when throttle rapidly opens and closes at the various engine conditions.