• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.6 s.99
• /
• pp.718-723
• /
• 2005

The purpose of this study is to present a fundamental data for evaluating aircraft noise of building site development. By the field experiments and the predicted equal noise level contours using the INM program, actual condition in the building site development arranged district was investigated. In order to get the results, Analysis of factors effected on noise level, sound level on the rate of increase to aircraft demand and difference on the aircraft noise levels according to floor level in apartment house was carried out. As a result the influence of the take-off and landing direction were appeared greatly. The influences of the height at receiving point, movement number of aircraft and increase to aircraft demand were appeared small And the influence of 1 day average WECPNL must be considered.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.996-1000
• /
• 2003

In this paper, Fly robot with electric power, a kind of Unmanned aerial vehicle (UAV), is considered as an autonomous hovering platform, capable of vertical lift-off, landing and stationary hovering. This aircraft has four rotor and DC motors of electrical Power, which is capable of omni-direction for indoor application. In the earlier days of vertical flight experimentation developers looked at the intuitively easy control functionality of 4 rotor designs. But we need to obtain design method of suitable structures and adequate components because the existing prototypes of 4 rotor-craft don't analyze the propeller, motor characteristic and propose a methodology to optimize this system. In this paper, we will show the new 4 rotor craft with blimp, analyze design and manufacturing method of 4 rotor craft system. Also we prove propriety of our design and manufacturing method by being based on thrust and motor experiment.

• International Journal of Aeronautical and Space Sciences
• /
• v.9 no.2
• /
• pp.58-63
• /
• 2008

This paper describes aerodynamic performance enhancement of cycloidal rotor according to the blade pivot point movement and the blade preset angle adjustment. Cycloidal blade system which consists of several blades rotating about an axis in parallel direction and changing its pitch angle periodically, is a propulsion mechanism of a new concept vertical take off and landing aircraft, cyclocopter. Based on the designed geometry of cyclocopter, numerical analysis was carried out by a general purpose commercial CFD program, STAR-CD. According to tills analysis, the efficiency of cycloidal rotor could be improved more than 15% by the introduced methods.

• Korean Journal of Applied Biomechanics
• /
• v.13 no.1
• /
• pp.155-171
• /
• 2003

The purpose of this study was to analyze the kinematic variables of over head kick(OHK) in soccer with three dimensional analysis technique and show the kinematic characteristics of it. The 7 subjects were university football player who have been playing football more than 7 years. The OHK was filmed on 16mm video camera(30frame/sec.) kinematic variables were temporal, postures, and COG(center of gravity). The mean values and the standard deviation for each variables were obtained and used as basic factors for examining characteristics of OHK. The results of this analysis were as follows : Temporal variables : The total time elapsed(TE) of OHK was $0.95{\sim}1.14sec$, the 1st phase was 0.35sec., 2nd phase was 0.46sec., and 3rd phase was 0.22sec.. Posture variables : When subjects performed OHK at the impact event, the ankle and knee angle of kicking foot were more extend than supporting foot. but the hip angle of supporting foot were more extend than kirking foot. Moving distance of the center of mass of the both foot. When subject performed OHK at the impact event, the range of distance on mediolateral direction aspect into right left shoulder line, anteroposterior direction aspect was $20.9{\pm}10.5cm$, vertical direction aspect was $92.3{\pm}19.9cm$. Angular velocity : the faster angular velocity of knee ankle on the kicking foot pew form jump position to landing position, the faster velocity of ball became. C. O. G. variables. When subject performed OHK at the impact event, upper part of the body was getting lower, lower part of the body was getting higher.

• Physical Therapy Korea
• /
• v.28 no.1
• /
• pp.84-91
• /
• 2021

Background: A hip fracture may occur spontaneously prior to the hip impact, due to the muscle pulling force exceeding the strength of the femur. Objects: We conducted falling experiments with humans to measure the activity of the hip muscles, and to examine how this was affected by the fall type. Methods: Eighteen individuals fell and landed sideways on a mat, by mimicking video-captured real-life older adults' falls. Falling trials were acquired with three fall directions: forward, backward, or sideways, and with three knee positions at the time of hip impact, where the landing side knee was free of constraint, or contacted the mat or the contralateral knee. During falls, the activities of the iliopsoas (Ilio), gluteus medius (Gmed), gluteus maximus (Gmax) and adductor longus (ADDL) muscles were recorded. Outcome variables included the time to onset, activity at the time of hip impact, and timing of the peak activity with respect to the time of hip impact. Results: For Ilio, Gmed, Gmax, and ADDL, respectively, EMG onset averaged 292, 304, 350, and 248 ms after fall initiation. Timing of the peak activity averaged 106, 96, 84, and 180 ms prior to the hip impact, and activity at the time of hip impact averaged 72.3, 45.2, 64.3, and 63.4% of the peak activity. Furthermore, the outcome variables were associated with fall direction and/or knee position in all but the iliopsoas muscle. Conclusion: Our results provide insights on the hip muscle activation during a fall, which may help to understand the potential injury mechanism of the spontaneous hip fracture.

• Korean Journal of Applied Biomechanics
• /
• v.13 no.3
• /
• pp.81-98
• /
• 2003

The purpose of this study is to closely examine kinematic characteristics by jump phase of Li Xiaopeng motion in horse vaulting and provide the training data. In doing so, as a result of analyzing kinematic variables through 3-dimensional cinematographic using the high-speed video camera to Li Xiaopeng motion first performed at the men's vault competition at the 14th Busan Asian Games, the following conclusion was obtained. 1. It was indicated that at the post-flight, the increase of flight time and height and twisting rotational velocity has a decisive effect on the increase of twist displacement. And Li Xiaopeng motion showed longer flight time and higher flight height than Ropez motion with the same twist displacement of entire movement. Also the rotational displacement of the trunk at peak of COG was much short of $360^{\circ}$(one rotation) but twist displacement showed $606^{\circ}$. Likewise, Li Xiaopeng motion was indicated to concentrate on twist movement in the early flight. 2. It was indicated that at the landing, Li Xiaopeng motion gets the hip to move back, the trunk to stand up and the horizontal velocity of COG to slow down. This is thought to be the performance of sufficient landing, resulting from large security of rotational displacement of airborne and twist displacement. 3. It was indicated that at the board contact, Li Xiaopeng motion made a rapid rotation uprighting the trunk to recover slowing velocity caused by jumping with the horse in the back, and has already twisted the trunk nearly close to $40^{\circ}$ at board contact. Under the premise that elasticity is generated without the change of the feet contacting the board, it will give an aid to the rotation and twist of pre-flight. Thus, in the round-oH phase, the tap of waist according to the fraction and extension of hip joint and arm push is thought to be very important. 4. It was indicated that at the pre-flight, Li Xiaopeng motion showed bigger movement than the techniques of precedented studies rushing to the horse, and overcomes the concern of relatively low power of jump through the rapid rotation of the trunk. Li Xiaopeng motion secured much twist distance, increased rotational distance with the trunk bent forward, resulting in the effect of rushing to the horse. 5. At horse contact, Li Xiaopeng motion makes a short-time contact, and maintains horse take-off angle close to vertical, contributing to the increase of post-flight time and height. This is thought to be resulted from rapid move toward movement direction along with the rotational velocity of trunk rapidly earned prior to horse contact, and little shave of rotation axis according to twist motion because of effective twist in the same direction.

• The Journal of Fisheries Business Administration
• /
• v.50 no.4
• /
• pp.29-44
• /
• 2019

This paper examines the trend of restructuring and direction of management response in the Large Purse Seine Fishery. The large-scale fishing industry is one of the most popular fishing areas in the coastal area, and it has been developed by providing exclusive supplies of many types of catchy fish, such as mackerel and horse mackerel through physical productivity in fleet operations. However, the Large Purse Seine Fishery has been declining in profitability due to the deterioration of the business environment since 2000. It is at a crossroads whether it will disappear or regenerate as it is. The Large Purse Seine Fishery's current problems are: firstly, the continued deterioration of the fishery business balance and worsening labor problems, secondly, insufficient freshness management and quality control after landing, and thirdly, import competition. The fourth is the intensification of the market competition, which is the evolution of fishing variability and the increase in the proportion of small fish. The fifth is the reduction of the operating fishing ground due to the suspension of mutual fishing in Korea and Japan. To address these problems and suggest management response directions for the survival of large-scale fishing businesses is as follows. First, a sustainable production system should be established through strengthening resource management and promoting international fisheries cooperation. Second, the profitability of fishing management should be improved by introducing a low-cost supplier system and securing a stable labor force. Third, we should improve the leading and quality control of catch, improve the high value-added value of catch through brand development, and secure competitive advantage with imported produce. Finally, the government should establish a cooperative system among private sector, government, and research institutes to push ahead with these tasks and strengthen the competitiveness of the front and rear industries.

• Journal of Advanced Navigation Technology
• /
• v.25 no.3
• /
• pp.242-247
• /
• 2021

Major countries in space field such as the United States, China and Russia have not only general ground-based space capabilities, but also maritime-based space capabilities. Maritime-based space systems include a maritime-based space surveillance system, a maritime-based space launch vehicle, and a maritime-based space information transmission system, and these maritime-based systems complement the ground-based space systems. Therefore, in this paper, we analyze the maritime-based space capabilities of major countries, and propose the future direction for south Korea's maritime-based space capabilities. The maritime-based space system is essential due to the geographical characteristics of south Korea, which has three sides of the ocean, and it is considered an one of important strategic element to become the seven major country in the space field.

• Journal of Mechanical Science and Technology
• /
• v.20 no.9
• /
• pp.1361-1370
• /
• 2006

An electronic beam mis-landing phenomenon on the RGB (red/green/blue) -fluorescent surface has been considered as one of serious problems to be solved in cathode-ray tube (CRT), which is generally caused by mechanical shock and vibration. In this work, structural design concepts on the major parts of the CRT, such as a frame, a shadow mask, and a spring, are studied to improve the mechanical shockproof character of a CRT by FEM-analyses and experimental approaches ; a frame is newly designed to have strength employing the double-corner-beads which reduces considerably the distortion of the frame and the shadow mask : the edge-bead of a shadow-mask is redesigned to maintain the wide curved surface of a shadow-mask after mechanical shock : finally, a spring supporting the frame and the shadow-mask is designed to have enough flexibility along drop-direction. As an example, a conventional type of a 15inch CRT was utilized to demonstrate the feasibility and usefulness of this work. Overall, some favorable information on the structural design of the CRT is achieved, and the mechanical shockproof character of a 15-inch CRT is improved in the degree of 3G $(1G=9.81m/s^2)$ as an average-value.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.4
• /
• pp.120-131
• /
• 2004

In this paper, we propose the method of a motion planning generation in which the movement of the 3-link leg subsystem is constrained to a slider-link and a singular posture can be easily avoided. The proposed method is the jumping control moving in vertical direction which mimics a cat's behavior. That is, it is jumping toward wall and kicking it to get a higher-place. Considering the movement from the point of constraint mechanical system, the robotic system which realizes the motion changes its configuration according to the position and it has several phases such as; ⅰ) an one-leg phase, ⅱ) in an air-phase. In other words, the system is under nonholonomic constraint due to the reservation of its momentum. Especially, in an air-phase, we will use a control method using state transformation and linearization in order to control the landing posture. Also, an iterative learning control algorithm is applied in order to improve the robustness of the control. The simulation results for jumping control will illustrate the effectiveness of the proposed control method.