• Tribology and Lubricants
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• 제5권2호
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• pp.48-54
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• 1989

The effects of angular misalignment, coning and the temperature difference between the primary seal ring and the seal seat on the pressure distribution in mechanical face seals are analyzed. The modified Reynolds equation for the temperature dependent viscosity was solved by a finite difference approximation and Gauss-Seidel method. It is shown that the amplitude of pressure is significantly affected by the misalignment of the seals and a large temperature difference between the rotor and the stator.

• 한국철도학회논문집
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• 제13권4호
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• pp.371-375
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• 2010

분산형 고속철도차량의 유리창 강도조건을 설정하기 위하여 열차가 터널을 통과하는 동안의 압력변동이 수치적으로 모사되었다. 계산결과를 토대로 객실 내외의 압력차이가 계산되었고, 객실 유리창에 작용하는 하중의 크기가 도출되었다. 열차가 터널을 통과하는 동안의 압력장을 모사하기 위하여 축대칭 Navier-Stokes 방정식에 기반한 전산유체역학이 이용되었다. 차량 내부의 압력변동은 차내 압력변화율과 차 내외부 압력변동의 선형 관계식에 근거한 1차 차분식을 이용하여 계산되었다.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1450-1456
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• 2003

Three-dimensional pipe flows with elbows, tees and headers in three different pipe systems are calculated to estimate the effect of asymmetry of axial velocity profile and swirl on measuring accuracy of an orifice flowmeter. It is evaluated how the pressure difference across the orifice is dependent on the upstream straight pipe length and how swirl intensity, swirl angle, and axial velocity distribution affect the measuring error of the orifice flowmeter. From the results, it is found that variation of the pressure difference across the orifice is negligible in case that maximum swirl angle is less than 2$^{\circ}$, and also that the pressure difference across the orifice is more sensitive to the asymmetry of axial velocity profile rather than the swirl intensity.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.130-135
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• 2009

These days, the super high-rise buildings construction plans are increased in Korea. But the stack effect in the super high-rise building interrupts the smoke control system's operation because of pressure difference, so it is more dangerous than the general building when firing. Therefore it needs to study about the pressure difference in the super high-rise buildings. We research the smoke control influence factor in the super high-rise building. Reflecting the influence factor, the simulation is practiced the case by case.

• 동력기계공학회지
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• 제18권2호
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• pp.31-36
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• 2014

In this paper, pneumatic valve which consists of valve body, valve controller, nozzle and a multi-bender PZT actuator was suggested and fabricated. The fabricated pneumatic valve was experimented for performance evaluation. From the experimental results, we know that the flow rate of the suggested valve is 23 lpm at the pressure difference of 1bar and the maximum flow rate is 30 lpm at the pressure difference of 4 bar. The flow rates after endurance test of 9.8 million were 22.57 lpm and 28.62 lpm at the pressure difference of 1bar and 4bar, respectably. Finally, it was verified that the B10 life of the suggested pneumatic valve is over 50 million.

• 한국운동역학회지
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• 제30권1호
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• pp.93-101
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• 2020

Objective: The purpose of this study was to differences of foot plantar pressure balance and lung capacity according to cervical posture in adults. Method: The subjects consisted of 33 adults in their 20s and 50s who use M centers in B-gu and H-gu, B-City, and they measured foot plantar pressure balance and lung capacity according to cervical posture (cervical normal curvature posture, cervical flexural posture) in adults. Results: In this study, the difference of foot plantar pressure balance according to cervical posture were analyzed. In the difference between left and right foot pressure balance. It was 1.50% increased in the cervical flexural posture than in the cervical normal curvature posture, and a statistically significant difference was observed. In the difference between the anterior and posterior foot pressure balance. It was 4.28% increased in the cervical flexural posture than in the cervical normal curvature posture, and a statistically significant difference was observed. The difference of lung capacity according to cervical posture were analyzed. In the PEF, It was 58.63 l/min decreased in the cervical flexural posture than in the cervical normal curvature posture, and a statistically significant difference was observed. In the FEV1, It was 0.15 ℓ decreased in the cervical flexural posture than in the cervical normal curvature posture, and a statistically significant difference was observed. Conclusion: The results of this study suggest that had a positive effect on differences of foot plantar pressure balance and lung capacity at cervical normal curvature posture in adults. In future research, itis believed that research on the elderly who have collapsed the normal curvature posture due to aging, as well as teenagers whose normal curvature posture due to the use of smartphones, will contribute to the balance of foot pressure and improvement of the right cervical habits. In future studies, it is also believed that it will be necessary to measure lung capacity after performing exercise according to the cervical posture, thereby providing sufficient oxygen during exercise to enhance the persistence and efficiency of the movement.

• 한국화재소방학회논문지
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• 제27권1호
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• pp.20-25
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• 2013

본 연구에서 부속실 단독 가압 구조인 급기가압 제연설비의 성능 확보에 영향을 주는 주요 매개 변수를 분석하고 공급유량과 누설면적 변화에 따라서 풍도와 부속실 차압 형성 관계를 실험적으로 분석하였다. 이를 위해서 3층 규모의 총 10개의 구획공간으로 구성된 모형 구조물과 방화문의 개폐력 측정장치를 제작하였으며, 각 구획공간과 외기의 차압, 방연풍속을 측정하기 위한 제어 계측 장비를 구성하였다. 그 결과 댐퍼의 차압조절 범위가 45 Pa~55 Pa인 경우 공급유량과 부속실 차압 크기에 따라서 45 Pa 이하인 저압 영역, 45 Pa~55 Pa 구간인 차압조절 영역 그리고 55 Pa 이상인 과압 영역을 구분하였으며, 저압 영역에서는 부속실, 차압조절 영역에서는 부속실과 댐퍼 그리고 과압 영역 에서는 댐퍼의 누설면적이 차압 형성에 중요한 관계를 갖고 있는 것을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권2호
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• pp.272-279
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• 2003

This study aimed to understand the effects of transporting ice slurry Particles through Pipes with branches. The experimental apparatus was constructed as ice slurry mixing tank. vortex pump, manometers for differential pressure measuring. IPF(ice packing factor) measuring instruments and branches as test sections. The experiments were carried out under various conditions. with concentration of water solution ranging between 0∼20wt% and velocity of water solution at the entry ranging between 1.5∼2.5m/s. The differential Pressure and IPF between the pipe entry and exit were measured. and flowing form was checked throughout the experiment. The pressure loss in 3d branches appeared compared with 6d branches so that it was very high. In the pressure loss of the inside and outside of branches. 6d branches was showed the difference. but was agreed in 3d branches The pressure loss according to concentration of water solution, low value appeared at 10wt% in 6d branches, at 20wt% in 3d branches. The pressure loss according to velocity, did not show large difference. The change of IPF at outlet, appeared +15∼-25% in 6d branches and 0∼-20% in 3d branches. The difference of IPF at the inside and outside of branches. appeared 10∼15% in 6d branches and maximum 5% in 3d branches.

• 설비공학논문집
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• 제13권11호
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• pp.1149-1155
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• 2001

The experimental investigation on energy separation in a vortex tube has been carried out to sow the effect of inlet and outlet pressures with various working fluids(air,$O_2,\;and\; CO_2$). Those outlet pressure means cold outlet and hot outlet pressure which were set equally. The results showed that the total enthalpy variation became a maximum when the mass flow rate at the cold outlet was a half of the total mass flow rate in the vortex tube (y=0.5). The total enthalpy variation was quite affected by the pressure difference between the inlet and outlet of vortex tube when the ratio of the inlet pressure to the cold outlet pressure remained constant. Although specific enthalpy differences between the inlet and the outlet (both cold and hot outlet) did not noticeably vary with the pressure difference, the specific enthalpy difference between the inlet and cold outlet was dominantly affected by physical properties of working gases.

• 한국운동역학회지
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• 제20권3호
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• pp.337-344
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• 2010

This study was conducted on male college students with pronated foot to measure the foot pressure by having them wear three kinds of mid-sole wedge ($0^{\circ}$, $5^{\circ}$, $10^{\circ}$). Maximum force, foot contact area, mean pressure and peak pressure were measured using a foot pressure distribution measuring instrument. And the surface of the foot sole was divided into 10 areas. Regarding maximum force, there were statistically significant difference in the area 3 of the middle foot(p<.05). Regarding the foot contact area, it appeared broad in the outside area(1, 3, 5) of the foot according to mid-sole wedge, and there was statistically significant difference in the area 1 of the rear foot(p<.05) and the area 3 of the middle foot(p<.05). Mean pressure by foot area decreased in the inside of the foot according to mid-sole wedge, and there was statistically significant difference in the area 2 of the rear foot(p<.05) and the area 3 of the middle foot(p<.05). Regarding the peak pressure by foot area, the pressure roughly decreased in the inside area(2, 4, 7) of the foot according to mid-sole wedge, and there was statistically significant difference in the area 1(p<.05), 2(p<.05) of the rear foot and the area 3 of the middle foot(p<.05).