• 국제물리치료학회지
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• 제1권2호
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• pp.176-184
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• 2010

This study was to investigate the effects of upper and lower limb composing patterns of PNF(proprioceptive neuromuscular facilitation) on the static balance ability by 20 subjects for 6 weeks. This study was measured left one leg standing and right one leg standing with closed eyes on Good Balance system. These results led us to the conclusion that the mean speed of X, Y direction, COP(center of Pressure) velocity moment showed a statistical decrease when applying post-exercise. The above results from this study indicated that upper and lower limb composing patterns of PNF exercise has improved the static balance ability. As a result, this study showed that upper and lower limb composing patterns exercise improve the ability of balance in young adults. Based on this study, it may be applied to old people.

• 드라이브 ㆍ 컨트롤
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• 제9권2호
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• pp.8-14
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• 2012

Electro-hydraulic spring return actuator(ESRA) is utilized for air conditioning facilities in a nuclear power plant. It features self-contained, hydraulic power that is integrally coupled to a single acting hydraulic cylinder and provides efficient and precise linear control of valves as well as return of the actuator to the de-energized position upon loss of power. In this paper, the algebraic equations of ESRA at steady-state have been developed for the analysis of static characteristics that includes control pressure and valve displacement of pressure reducing valve, flow force on flapper as well as its displacement over the entire operating range. Also, the effect of external load on piston deviation is investigated in terms of linear system analysis. The results of static characteristics show the unique feature of force balance mechanism and can be applied to the stable self-controlled mechanical system design of ESAR.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1957-1962
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• 2004

The objective of this study is to perform the numerical investigation of flow characteristics in static mixers. Simulations are carried out for mixers consisting of up to six Kenics and PPM elements placed end-to-end at an angle of $90^{\circ}$and for a range of Reynolds number($1{\leq}Re{\leq}100$). The pressure drop across a six-element Kenics mixer is computed and compared with the previous experimental correlations. The results are in good agreement with the previous correlations. The simulated flow field of Kenics mixer is extremely complex and contains regions of transverse flow that is dominated by the interaction of vortices produced by the mixer elements.

• 대한기계학회논문집B
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• 제32권5호
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• pp.392-399
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• 2008

Accurate measurement of speed and altitude of flying vehicles in air data system remains a critical technical issue. A highly reliable Pitot-static probe is required to obtain air data such as total pressure and static pressure. In this study, an analysis of the characteristics of flowfield around the Pitot-static probe was performed by using a Navier-Stokes CFD code. In addition, for the purpose of finding an optimal configuration, a technique based on the response surface method is applied to the problem with design parameters including shape of the nose section and cone angle. It is shown that the optimal configuration fulfills the MIL specification in wider range of high angles of attack.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
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• pp.62-70
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• 1999

Artesian pressure exists in Yangsan site, the maximum value of which has been measured as high as 5 t/m$^2$. This paper deals with the prediction of consolidation settlement for the site with artesian pressure. The consolidation settlement at the site has been accelerated using vertical band drains. Since the artesian pressure gives lower effective stress than a static condition, its effect should be considered in the settlement prediction. This case study shows that the prediction of settlement and pore pressure dissipation agrees well with the measurements, when considering the artesian effect.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.163-167
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• 2008

30톤급 액체로켓엔진 연소기 연소시험을 통해 측정된 압력섭동 특성에 대한 결과를 제시하였다. 연소실 압력과 O/F비를 변화시키면서 수행된 46회의 연소시험의 결과를 바탕으로 30톤급 연소기의 연소 안정성을 대해 평가하였다. 정상 연소과정에서 발생하는 압력섭동 RMS 값이 연소실 압력의 2.6% 이내로서 정상상태에서 연소현상이 안정적임을 보여주었다. 또한 펄스건 강제교란을 통한 압력섭동의 감쇠 시간 계산결과가 3.5 msec 이내라는 것을 통해 동적으로 안정적인 연소기임을 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제9권4호
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• pp.32-41
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• 2012

Most diagnosis methods for servo valves requires installing spool displacement sensor or flow sensor as well as pressure sensor. The measurement of flow is hard to implement and many kinds of servovalves or proportional direction valves do not have a built-in spool displacement sensor. In this study, static performances of servovalve or proportional-direction-valve are studied theoretically and a diagnosis technique, which uses only load pressure and input current signal, is assessed. An experimental setup was made based upon a personal computer and the LabVIEW graphical language. A series of diagnosis tests were performed and the analysis results showed it possible to measure the pressure gain, hysteresis and null bias in a relatively simple methodology.

• 설비공학논문집
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• 제20권1호
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• pp.17-25
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• 2008

To achieve the unidirectional airflow in a cleanroom, we need to predict accurately the static pressure losses at the lower plenum and to control properly the opening pressure ratio of access floor panels based on these pressure losses. At first, the present study proposed a correlation to predict the velocity distribution at the lower plenum, because the accuracy to predict pressure losses at the lower plenum depends on how to calculate the velocity correctly against the inner structures at the lower plenum. In the second place, this study proposed correlations which considered the effect of inner structures such as columns, ducts and equipments at the lower plenum on pressure losses. In order to test the accuracy of these correlations, we compared air flow patterns before regulating the opening ratio of access floor with those after regulating. Results after regulating the opening ratio of access floor show good unidirectional uniform airflow pattern. So the present method can be used as an important tool to control the air flow in a cleanroom.

• Geomechanics and Engineering
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• 제17권4호
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• pp.393-403
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• 2019

The cycling impact test of red sandstone soil under different axial pressure and different impact loads are conducted to reveal the mechanical properties and energy consumption mechanism of red sandstone soil with static-dynamic coupling loading. The results show that: Under the action of different axial pressure and different impact loads, the peak stress of the specimen increases, and then tends to be stable with the times of impact. With the increase of impact times, the specific energy absorption value of the red sandstone soil specimen is increased first and then gentle development trend. When the impact loads are certain, the larger the axial pressure is, the smaller the peak value of energy absorption, which indicates that the energy utilization rate is not high under the condition of large axial pressure. Through the analysis of energy utilization, it is found that the smaller the impact load, the higher the energy utilization rate. The greater the axial pressure, the lower the energy utilization rate. when the axial pressure is large, the impact loads corresponding to the maximum values of reflectivity, transmissivity and absorptivity are the same. The relationship between reflectivity and transmissivity is negatively correlated.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1178-1186
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• 2002

Clean stockers are being used by semiconductor and TFT-LCD manufacturers to store and buffer work in process. The only way to keep the stored product clean is to provide constant clean airflow the product and through stocker. Up to now, stockers typically have been configured to receive their laminar airflow from fan filter units that are located on the side of the stocker. This type of stocker may have such problems as complexity of structure, increment of temperature, mechanical vibration, initial investment and running cost. In this study, in order to solve the above mentioned problems, new air control system in stocker is proposed, which is to control open ratios of exits that are located on the side of the stocker without fan filter units. In this study, static pressure regain was used for the analysis of the open ratios of exits theoretically and experiment was also conducted using actual clean stocker for TFT-LCD manufacturers and CFDesign, was used for simulating airflow in stocker. As a result, open ratios of exits can be obtained by the analysis of static pressure regain and was verified by experiment and simulation results. Therefore, new air control system in stocker can be used by the semiconductor and TFT-LCD manufacturers.