• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.498-501
• /
• 2000

Air dynamic bearings are inherently unstable in dynamic behavior due to the varying angle of a force produced and the nonlinear characteristics of stiffness. In this study, such dynamic behavior is obtained and compared with experimental results. A body axis coordinate system is employed to avoid the change of a moment of inertia. FDM is used to calculate the pressure distribution on the bearing surface and then the force acting on the rotor was calculated by integrating the pressure distribution. By integrating accelerations which are calculated from the equations of motion using the 4th order Runge-Kutta method, the pose of the bearing at each time step is obtained.

• Science of Emotion and Sensibility
• /
• v.2 no.1
• /
• pp.95-103
• /
• 1999

침대에서의 체압분포는 수면 안락감에 중요한 영향을 미치는 요인중의 하나로 고려되어져 왔다. 체압분포는 사람의 몸무게에 의하여 침대와 누운사람 사이의 접촉면에서 발생하는 압력의 분포를 말한다. 안락한 체압분포 패턴을 결정하기 위하여 사용자가 침대 8부분의 높이를 조절할 수 있는 가변침대를 사용하였다. 체압분포 측정은 각 수면자세(바로 누운 자세, 옆으로 누운 자세, 엎드린 자세)에서 가변침대의 초기상태와 피실험자가 편안한 체압분포 패턴을 유지하도록 높이를 조절한 상태에서 이루어졌다. 본 연구에서는 각 수면자세에서 체압비와 선호하는 체압비의 특징을 알아보았다. 본 연구의 결과를 요약하면 다음과 같다. - 각 수면자세에서 엉덩이 부분의 체압비가 가장 높았으며, 바로 누운 자세는 40% 이상의 체압비가 엉덩이에 집중한다. - 각 수면자세에서 전체적으로 머리와 다리의 높이가 다른 부분보다 높은 것을 선호하는 경향을 나타난다. - 바로 누운 자세에서는 유추를 기준으로 신체가 W형이 되도록 머리, 요추, 대퇴부분의 높이를 올리는 것을 선호한다. - 엎드린 자세는 머리와 다리부분의 높이를 증가시킴으로써 신체이 곡선이 U형이 되도록 하는 것을 선호한다.

• Journal of the Ergonomics Society of Korea
• /
• v.11 no.2
• /
• pp.23-33
• /
• 1992

The distribution of the pressure between the sole of a feet and a supporting surface can reveal the information about the structure and fonction of the foot and the posural control of the whole body. In particular, the measurement of the vertical contact forces between the plantar surface of the foot and the shoe insole is of great importance to reveal the loading distributio patterns incurred from a particular shoe midsole design. In order to investigate the plantar surface pressure distribution, an insole-type sensor with a piezoelectric material is developed and tested. The present paper describes a new method to completely reduce both the shear force and pyroelectric effects that are normally caused from piezoelectric materials.

• Journal of the Ergonomics Society of Korea
• /
• v.33 no.1
• /
• pp.59-68
• /
• 2014

Objective: The aim of this study is to investigate the effect of BackJoy on how it effectively reduces the physical load generated in a posture in which the user sits, increases user's comfort and satisfaction, and maintains the correct posture. Background: Because of development of science and economic development, most office workers and students spend about 75% of their working time in chairs. However most of them have a poor posture. Method: This experiment conducted measurement using a pressure mat and surveyed to evaluate fatigue level, satisfaction and comfort of sit. The study is experimented 20 male and 14 female participants. The participants carried out four different types of tasks and each task took 20 minutes long. Results: In the case of experiment results before and after the use of BackJoy, average pressure, contact area and pressure per unit area appear to prove that using BackJoy is more effective. Conclusion: Through this study, the BackJoy's effects for the maintenance of good posture and loads that occur in the body are reduced. In the future study, there are some researches needed for various verifications using an EMG sensor that shows loads of vertebrae and we need to analyze each group of the participants by dividing them. Application: The evaluation method used in this study can be applied to evaluating ergonomic chairs.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.7 no.3 s.18
• /
• pp.69-76
• /
• 2004

In this paper, an efficient inverse design method for nose shape of submerged body based on the MGM(Modified Garabedian-McFadden) design method has been developed. The MGM design method is a residual-correction technique, in which the residuals are differences between the desired and the computed pressure distributions. 3-D incompressible Wavier-Stokes equation was adopted for obtaining the surface pressure distribution and combined with the MGM design method to perform the inverse design of nose shape of submerged body. The design method was verified by applying to several airfoil shapes. Improved design shapes could be obtained when the method was applied to nose shapes of submerged body.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.3
• /
• pp.237-243
• /
• 2010

In this study, the effect of the shape of a pintle(obstacle) on thrust-modulation performance and drag in a pintle rocket was investigated by a cold flow test and by computational fluid dynamics. Pintle movement caused a monotonic increase in the chamber pressure. Thrust generated by the pressure distribution on the pintle body was linearly changed to the chamber pressure, and this thrust was greater than that generated by the nozzle-wall pressure distribution. Because the shock pattern in the nozzle changes with the shape of the pintle body and pressure ratio, the thrust generated by the nozzle-wall pressure is not directly affected by chamber pressure. The drag due to the pintle(obstacle) can be minimized for a fully linear pintle shape, regardless of chamber pressure.

• Korean Journal of Human Ecology
• /
• v.15 no.4
• /
• pp.647-650
• /
• 2006

The factors affecting clothing comfort are temperature, humidity, and air velocity of clothing microclimate which is the temperature and the humidity between the skin surface and the innermost garment, clothing pressure and clothing texture to the skin. This study was designed to estimate the distribution of clothing microclimate on the upper body. All the data of this study were collected from volunteered male subjects in the controlled climate chamber laboratory in which the temperature was $25\pm1^{\circ}C$, the relative humidity $50\pm5%$, and the air velocity 30cm/sec. All subjects should wear long-sleeved inner wear and pants woven in 100% cotton. Clothing microclimate temperature at 16 sites on the chest and 16 sites on the back was measured. The results were as follows: the distribution of the clothing microclimate temperature on the upper body was $30.6\sim34.7^{\circ}C$ on the breast and $31.5\sim35.4^{\circ}C$ on the back. While a mean temperature on the chest was 33.3$^{\circ}C$, it was 33.1$^{\circ}C$ on the back.

• The Journal of Korean Medical History
• /
• v.23 no.1
• /
• pp.23-41
• /
• 2010

Greater yang disease(太陽病) is a syndrome induced by peripheral obstruction. One of them is "wind stroke(中風)" with the obstruction in lymphatic system. The other obstruction appearing on circulatory system is called "cold damage(傷寒)." Kyejitang(桂枝湯) is the formula prescribed for greater yang wind stroke pattern(太陽中風證) which is caused by peripheral lymphatic duct obstruction. Ramulus Cinamoni acts as a vasodilator and Radix Paeoniae relieves the abdominal tension. They make blood move to the internal organ and this can remove the retention of peripheral lymphatic system. Covering the patient with a blanket and getting him/her to have hot and thin rice gruel causes slight Diaphoresis, contributing to relieving the retention of lymphatic system. Disharmony between nutrient and defense(營衛不和) means that pressure becomes different between lymphatic system and vascular system. Kyejitang(桂枝湯) is called releasing muscles formula(解肌劑) because it can resolve such pressure difference. Diaphoresis is not a means to eliminate pathogenic qi(邪氣) from the body. That is the syndrome proving that the body fluid has moved around when disordered fluid distribution is corrected. Therefore, diaphoresis should be induced weakly all the time. If diaphoresis is induced excessively, body fluid will move more than desired and then illness cannot be cured. In Sanghanlun(傷寒論), dispersing drugs aim at addressing the retention in the exterior field, but it actually applies to the entire exterior and interior to make body fluid move. Therefore, diaphoresis does not just act on exterior field, and freeing the stool does not only apply to interior field. Distribution of body fluid changed by pathogenic qi(邪氣) influences the whole body because the human body has a closed circulatory system. Sanghanlun(傷寒論) has included treatments for pathogenic disease. However, its value should not be limited to pathogenic disease. It is because controlling blood flow by sending body fluid to the place a doctor wants is certainly worth using for treatment of non-exogenous disease or chronic illnesses.

• Fashion & Textile Research Journal
• /
• v.18 no.4
• /
• pp.457-467
• /
• 2016

This study aimed to develop functional underwear for elderly women in their sixties in terms of good fit, wear comfort and body temperature regulation. To satisfy elderly women's physical and metabolical needs, an automatic temperature control system via PCM treatment was applied. Underwear pattern was produced by producing body surface replica, which was derived from 3D body parametric model. Differential ratios of outline length and area between 3D surface and 2D plane were 1.4% and 0.5%, respectively. The reduction rate was determined as 10% through the expert's evaluation. PCM treated fabric showed higher Q-max, meaning that it can facilitate the thermal transition in hot situation. Moreover, it also showed higher insulation to preserve heat and keep warm microclimate in a cold weather. Heat distribution measurements on various body parts revealed that the temperature after PCM treatment was significantly higher. The clothing pressure after 10% pattern reduction showed higher before reduction, at the same time, even lower than the comfort clothing pressure range of $5{\sim}10gf/cm^2$, implying that experimental garment of this research is acceptable in terms of clothing pressure. Evaluation results on the comfort to move in various motions proved that adequate clothing pressure improved the wear comfort in various motions.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.10
• /
• pp.974-984
• /
• 2012

This research introduces a new method to attenuate flip-over vibration generation in the flat blade windshield wiper by adjusting the contact pressure between the windshield glass and the blade. The knocking force in the flip-over action of the blade is decreased by inducing gradual tilting-over along the rubber strip of the blade. This gradual tilting-over is induced by introducing a non-uniform contact pressure distribution between the blade and windshield glass. The contact pressure distribution is adjusted by controlling the unloaded profile of the body spring in the blade using a procedure proposed in a previous study. Two blades, one blade designed to generate a uniform pressure distribution and the other designed to generate non-uniform pressure distribution, are developed using the procedure. Contact pressure distributions of the developed blades are measured using a special device and compared with the intended distributions confirming the similarities between the two groups. Vertical and lateral vibrations of the two blades are measured under realistic operating condition simulated by a wiper test rig. The vertical vibrations of the blade with non-uniform contact pressure are substantially smaller than corresponding vibrations of the blade with uniform contact pressure over the entire rubber strip.