• Journal of Advanced Marine Engineering and Technology
• /
• 제25권2호
• /
• pp.331-337
• /
• 2001

A numerical simulation of the temperature rise for sliding surface in dry contact is based on Jaegers formula combined with a calculated heat input. A gear tooth temperature analysis was performed. The pressure distribution has the Hertzian pressure distribution on the heat source. The heat partition factor is calculated along ling of action. A Temperature distribution of tooth surface is calculated about before and after profile modification. A Temperature of addendum and deddendum in modified gear have reduced.

• International Journal of Korean Welding Society
• /
• 제1권1호
• /
• pp.13-16
• /
• 2001

High speed seam weldability of tin coated steels was investigated. Welding was performed by the laboratory wire seam welder that was equipped with process monitoring system Test results showed that increase in applied current and pressure reduced the total resistance across the welding electrodes. Lower and upper limits of welding current increased as the sheet thickness increased, while the acceptable welding condition range decreased. However, extremely low electrode pressure produced unstable welding condition range. The results also demonstrated that slower welding speeds widened the optimum welding heat input range.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.1136-1137
• /
• 2006

The ultrahigh pressure process for synthesizing diamond grits is due to make a quantum leap: the raw materials will incorporate diamond seeds with a predetermined pattern. The result is doubling the diamond yield with a narrower size distribution. Moreover, the shape of diamond crystals can be precisely tuned. For example, diamond octahedra or diamond cubes, that are not available today, can be mass-produced. The new technology is now being implemented worldwide so the future diamond grits will have improved quality at reduced prices.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1934-1937
• /
• 1999

A copper-tungsten sintered alloy(Cu-W) has been friction-welded to a tough pitch copper (Cu) in order to investigate friction weldability. The tensile strength of the friction welded joint was increased up to 87% of the Cu base metal under the condition of friction time 1.0 see, friction pressure 40MPa and upset pressure 100MPa, upset time 5.0 sec. And it is related to upset pressure rather than friction time. Mixed layer was formed in the Cu adjacent weld interface and W particles which were included in mixed layer could induce fracture in the Cu adjacent to the weld interface. Thickness of mixed layer was reduced as upset pressure increase.

• 동력기계공학회지
• /
• 제9권2호
• /
• pp.45-49
• /
• 2005

Liquefied natural gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high-pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high-pressure LNG pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current signal analysis have been performed. High vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2000년도 추계 학술대회논문집
• /
• pp.141-148
• /
• 2000

The discrete noise of the cross-flow fan with uniform/random pitch blades is predicted by computational methods. With the time dependent surface pressure data obtained by solving the Wavier-Stokes equation, the acoustic pressure is calculated by the Ffowcs Williams-Hawkings equation. The positions of the blade noise source are identified through investigation of the acoustic pressure history induced by one blade, and it is confirmed that the dominant noise source is near the stabilizer. Since the acoustic pressure of the random pitch fan fluctuates according to blade passing, the dominant BPF noise for the uniform pitch fan is modified into some reduced discrete noises which have a 50Hz difference from BPF.

• 센서학회지
• /
• 제5권2호
• /
• pp.1-8
• /
• 1996

본 논문에서는 감도를 향상시키고 저압력 범위에서 다이어프램의 휨을 감소시킴으로서 선형성이 향상되도록 한 센터 보스(center boss) 다이어프램 구조를 갖는 압력센서를 설계 하였다. 설계한 센터보스형 압력센서의 최대 휨은 $0.125{\mu}m$, 최대 응력은 $2.24{\times}10^{7}\;Pa$, 최대 스트레인은 $132\;{\mu}strain$, 감도는 27.67 mV/V.psi로서 휨은 다이어프램 두께의 약 1/160, 정사각형 구조일때의 1/35로 감소하였고 감도는 정사각형 구조일때보다 19배정도 증가하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.776-779
• /
• 2005

Liquefied Natural Gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high Pressure LNG pumps determined the send out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current analysis have been performed. And high beat vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• Journal of Chest Surgery
• /
• 제23권2호
• /
• pp.245-252
• /
• 1990

To see the change of pulmonary arterial pressure after mitral valve replacement, postoperative cardiac catheterization and echocardiographies were performed in 12 patients of mitral valvular disease with pulmonary hypertension[systolic pulmonary arterial pressure>50 mm Hg]. The mean follow-up duration was 35.4[range: 15-47] months per patient. The following results were obtained. 1] Preoperative systolic pulmonary arterial pressure value of 66.17\ulcorner10.73mmHg decreased significantly to 29.17\ulcorner6.86mmHg postoperatively[p<0.01]. 2] Preoperative Pp/Ps value of 0.67\ulcorner0.13 decreased significantly to 0.28\ulcorner0.06 postoperatively[p<0.01]. 3] Preoperative PAWP value of 29.00\ulcorner4.02mmHg decreased significantly to 9.92\ulcorner4.27 mmHg postoperatively[p<0.01]. 4] Preoperative LAD value of 5.58\ulcorner1.20cm decreased significantly to 4.37\ulcorner0.67cm postoperatively [p<0.01]. In conclusion, pulmonary arterial hypertension secondary to mitral valvular disease could be reduced to normal range after successful mitral valve replacement.

• 한국정밀공학회지
• /
• 제16권12호
• /
• pp.31-39
• /
• 1999

Previous researches and experiments have already verified that the primary noise source of high pressure tandem axial thpe piston pump is fluid-borne noise from the process of oil distribution between the kidney-shaped port and valve plate. So, many researchers have improved pressure gradients and reduced sound levels by applying pre-compression and pre-decompression metering grooves to valve plate. In practice however, the sound level of th high pressure tandem axial type piston pump is still undesirable. This paper testified the effect of pumping phase of the piston on vibration and noise of th high pressure tandem axial type piston pump on the best of theoretical research in $this^(1)$. Therefore considering the pumping phase of the piston when assembling the tandem axial type piston pump, it is possible to reduce 1.5~2[dB]of sound level.