• 한국기계가공학회지
• /
• 제15권4호
• /
• pp.148-154
• /
• 2016

A study on the micro particle blasting was conducted to find the optimum conditions of the blasted surface of aluminum 6061. The particle type such as $Al_2O_3$ and SiC, nozzle diameter, pressure, standoff distance and injection time were used as blasting conditions. Statistical method of orthogonal arrays(ANOVA) was used to find optimum conditions of maximum depth and maximum diameter of blasted surface. Particle type, nozzle diameter, and pressure were found to be the main factors of maximum blasted depth and diameter. Maximum blasted diameter was affected by increasing pressure and nozzle diameter but saturated maximum diameter. Maximum blasted depth was affected by pressure and nozzle diameter when aluminum 6061 was blasted with $Al_2O_3$ particle. The value of surface roughness was increased as pressure and nozzle diameter increased when aluminum 6061 was blasted with SiC.

• 한국가스학회지
• /
• 제8권4호
• /
• pp.50-54
• /
• 2004

Methyl Ethyl Ketone Peroxide의 분해폭발로 인한 폭발의 위험성을 평가하기 위하여 소형압력용기 시험기(MCPVT)를 사용하여 실험을 하였다. 그 결과 최대폭발 압력은 MEKPO와 MEKPO에 $98\%H_2SO_4$의 첨가량이 $1\%,\;3\%$ 및 $5\%$로 증가할 수록 증가하였으며, 최대폭발압력상승 속도도 증가하였다. 또한 분해개시 압력하에서의 온도는 $H_2SO_4$의 첨가량이 증가할수록 $168.16^{\circ}C,\;126.76^{\circ}C,\;91.21^{\circ}C$ 및 $81.25^{\circ}C$로 낮아졌다.

• 한국생산제조학회지
• /
• 제22권3_1spc호
• /
• pp.573-579
• /
• 2013

Once-through helically coiled steam generator tubes subjected to external pressure are of interest because of their application to advanced small- and medium-sized integral reactors, in which a primary coolant with a relatively higher pressure flows outside the tubes, while secondary water with a relatively lower pressure flows inside the tubes. Another notable point is that the values of the mean radius to thickness ratio of these steam generator tubes are very small, which means that a thick-walled cylinder is employed for these steam generator tubes. In the present paper, the maximum allowable pressure of helically coiled and thick-walled steam generator tubes with through-wall cracks under external pressure is investigated based on a detailed nonlinear three-dimensional finite element analysis. In terms of the crack orientation, either circumferential or axial through-wall cracks are considered. In particular, in order to quantify the effect of the crack location on the maximum external pressure, these cracks are assumed to be located in the intrados, extrados, and flank of helically coiled cylinders. Moreover, an evaluation is also made of how the maximum external pressure is affected by the ovality, which might be inherently induced during the tube coiling process used to fabricate the helically coiled steam generator tubes.

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권3호
• /
• pp.457-465
• /
• 2004

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the performance and the emission characteristics of 4 stroke marine diesel engines for generation application in D2 cycle(IMO mode). The effects of important operating parameters, such as intake air pressure. intake air temperature and maximum combustion pressure on NOx emissions were also described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. But NOx emission is not affected by intake air pressure and exhaust gas back pressure.

• Korean Journal of Hydrosciences
• /
• 제7권
• /
• pp.77-86
• /
• 1996

An air chamber is design to keep the pressure from exceeding a predetermined value, or to prevent low pressures and colum separation. Therefore, it can be used to protect against rapid transients in a pipe system following abrupt pump stoppage. In this research, an air chmber was applied to a hypthetical pipe system to analyze attenuation effect of pressure head for different air volumes, locations, chamber areas, coefficients of orifice loss and pollytropic exponents. With an increase of air volume, the maximum pressure head at pump site is decreased and the minimum pressure head is imcreased. For different locations and areas of the chamber, the attenuation effects do not show much difference. Also, as the orifice loss coefficient increases, the maximum pressure head is decreased. For different polytropic exponents, isothermal process shows lower maximum pressure head than that of the adiabatic process.

• 한국운동역학회지
• /
• 제19권4호
• /
• pp.771-778
• /
• 2009

본 연구는 구두 굽 높이 변화에 따른 보행 시 족저압력을 비교, 분석함으로써 구체적인 데이터를 정량화하여 높은 굽을 착용함으로 인한 전족부의 압력 증가가 발에 미치는 영향을 알아보고자 한다. 본 연구에 사용된 구두는 선행연구를 바탕으로 여대생이 선호하는 구두 굽 높이 3cm, 7cm를 선택하였으며 여대생 10명을 대상으로 발을 전족부와 후족부로 나누어 수직힘, 최대압력, 평균압력을 측정하였다. 그 결과 전족부에서의 평균압력은 7cm 높이 구두가 높게 나타났으며, 후족부에서는 7cm 높이 구두가 낮게 나타났다. 통계처리 결과 전족부위에서는 3cm 굽 높이와 7cm 굽 높이의 최대압력 비교에서 유의한 차이가 나타났으며(p<.05), 후족부위에서는 수직힘, 최대압력, 평균압력 모두 유의한 차이가 나타났다(p<.05). 이상과 같이 구두를 착용함으로서 전족부의 최대압력이 높아지는 것은 물론이고 후족부위의 수직힘, 최대압력, 평균압력도 높아지는 것을 알 수 있었다. 이러한 현상은 전족부위에 높은 압력분포로 구속압이 증가하여 발가락의 변형을 유발할 수 있으며 후족부위에 압력증가는 장시간 착용 시 뒤꿈치의 통증을 유발할 수 있다. 따라서 굽이 있는 구두를 착용할 때 굽 높이가 7cm일 때 보다는 3cm일 때, 굽 높이가 낮을수록 전족부의 변형 예방과 후족부의 통증을 줄일 수 있을 것으로 기대된다.

• 대한기계학회논문집B
• /
• 제26권10호
• /
• pp.1472-1479
• /
• 2002

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke marine diesel engines in E3 cycle (propulsion application) and D2 cycle (generation application). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure on the specific emissions are described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that NOx emission level in E3 cycle is higher than that in D2 cycle due to lower engine speed at low load and the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
• /
• pp.121-127
• /
• 2002

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke propulsion diesel engine in E2 cycle (constant speed) and E3 cycle (propeller curved speed). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure are described on the specific emissions. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that NOx emission level in E3 cycle is higher than E2 cycle due to lower engine speed and lower maximum combustion pressure by retarding fuel injection timing. Intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.

• Korean Journal of Acupuncture
• /
• 제38권4호
• /
• pp.308-316
• /
• 2021

Objectives : This study aimed to develop a cupping pressure control valve for limiting maximum negative pressure while achieving clinical therapeutic outcomes to minimize side effects induced by excessive negative pressure of air extraction cupping devices. Methods : To determine the clinical necessity and suitability of the cupping pressure control valve, this study was designed to measure the change in pressure with or without the valve using both a manual and an electric suction pump. Results : While the maximum pressure was limited by the pressure control valve, the pressure did not increase above a certain level regardless of the type of manual or electric pump. Conclusions : This study will contribute to the development of a safer and more effective base technology for cupping treatment in oriental medicine.

• 대한인간공학회지
• /
• 제25권3호
• /
• pp.17-24
• /
• 2006

In this paper, we propose a stress analysis on foot by lifting task attitudes. Maximum force and peak pressure were measured on 8 body regions by Pedar system in order to analysis the stress which is affected by task style and angle on foot when Manual Materials Handling task. As for the peak pressure of the whole foot as to the task height during the lifting task, the height from Knuckle to Shoulder was the least in the peak pressure. Also, as for the maximum force and the peak pressure of the whole foot as to the task angle during the lifting task, it could be seen that the more an angle increases, the stress influencing on a foot jumps. As for the maximum force and the peak pressure by foot region as to the task height in case of the lifting task, the height from Knuckle to Shoulder is indicated the smallest value in the maximum force and the peak pressure, thus there is necessary to attain the work design that considered this. Also, as for the maximum force by foot region as to the task angle in case of the lifting task, 0° tasking is indicated to be least, thus there is necessity to be attained the tasking design in a bid to prevent the existence of an angle. The results of this paper are thought to be helpful to the suitable work design, to the prevention of musculoskeletal disorders related to the lower limbs, and to the design of ergonomic safety shoes.