• Journal of Biosystems Engineering
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• v.12 no.1
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• pp.45-52
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• 1987

In order to improve the thermal efficiency of an internal combustion engine, various ignition timing control systems were examined and the best one was chosen. The parts used for the systems were a microcomputer system with DAS, 8 bit output port (D-FLIP FLOP), three types of isolation circuit, two types of ignition timing pulse generator, three types of switching circuit and two types of high voltage ignition circuit. Most systems did not operate well due to the effects of electromagnetic waves and surge currents occurring when the ignition began or ended with resulting high voltage. The best ignition timing control system was found to be the combination of (microcomputer system)-(ignition timing pulse generator using step motor position control pick-up)-(switching circuit using TR logic)-(high voltage ignition circuit using CDI).

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.76-86
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• 2018

Using the CAPSS emissions data, we analysed changes and reasons in the annual air pollutant emission trends from 1999 to 2014. The CO emissions in the metropolitan area decreased steadily since 2001, when the latest model year of automobiles and high efficiency fuel were applied. However, other regions have not changed significantly in annual emissions. $NO_x$ emissions continued to increase since 2003, and unchanged after the decline in 2007. $SO_x$ emissions are steadily declining due to the supply of low sulfur oil. The $PM_{10}$ and $PM_{2.5}$ emissions were repeatedly affected by the influence of motor vehicles activities in the metropolitan area. In Gangwon and Chungcheong Provinces, emissions are increasing according to the use of coal in the manufacturing sector. And VOC and $NH_3$ emissions are increasing steadily every year. The major CO emission sources was automobiles in the metropolitan area. However, agricultural residue burning was the biggest CO sources in the Chungchong, Honam and Yeongnam Provinces. The major sources of $NO_x$ emissions differ from region to region. In the Metropolitan area, Honam and Yeongnam region, the truck was the largest emitter of $NO_x$. However, the cement kiln was the largest producer of $NO_x$ in Gangwon region, and the power plant is the largest emitter in Chungcheong Provinces.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1483-1490
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• 2011

Electro-hydrostatic actuators(EHAs), which are usually composed of a direct motor-driven hydraulic pump and a cylinder, have been widely adopted as aircraft actuation systems because of their benefits in terms of improved efficiency, weight savings and the fact that they use a standalone power source. Since the recent trend in construction vehicles has been focus on energy savings in their hydraulic systems, EHAs are expected to be potential substitutes for conventional power transmission, since they are capable of energy recovery as well as highly efficient pump control. In this paper, the start and stop characteristics of EHAs were investigated through cracking pressure analysis of the pilot-operated check valve(PCV), which enables the cylinder to standstill against an external load with no holding effort from the hydraulic pump. A mathematical model that includes the load dynamics and the EHA's internal hydraulic circuit was derived for simulation with the MATLAB Simulink package. This model verified the PCV's opening and closing sequence, which in turn affects the EHA's start and stop characteristics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.203-207
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• 2007

In this study, the combustion characteristics of HTPB was studied in hybrid propulsion system. In this experiments HTPB was used as fuel, GOX was used as oxidizer. The mass flow rate of GOX was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $13.8{\sim}42.7g/sec$. The experimental result of HTPB was compared with the other studies of HTPB, and the combustion performance of HTPB was analyzed with that of PE. As a result, the homing rate and efficiency of HTPB as fuel were better than that of PE in the same hybrid motor.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.3
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• pp.229-234
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• 2007

Currently offshore fisheries are one of shrinking industries and fishermen are getting older. Moreover it is difficult to work fisheries for decreasing fishermen as the time goes. Two people per a boat work together at least for proper fisheries. If the unskilled fisherman boards on boat, it will make some troubles to speak each other and diminish the efficiency of working because one person should control the boat. So it need to study the remote control system for leasure and outboard engine that can control and work at the same time. The remote control system is consisted of engine, steering gear and forward reverse neutral gear controls. These three controls are made by position and speed control using DC motor, and microcontroller is used to control the engine speed and rudder angle. This system can be controled and worked alone and we tested the system at sea and confirmed that the system works properly.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.1
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• pp.65-72
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• 2016

In this study, a fully active transfemoral prothesis with a knee joint is designed considering stair walking conditions. Since the torque at the knee joint required for stair walking condition is relative high compared with the one in normal walking condition, the proposed design has high torque generating mechanism. Moreover, the transfemoral prothesis is designed in compact size to reduce its weight, which is related to comfortable fit and fatigue of patients. Flat type BLDC motor is used for simple and compact structure and various components are used to generate required torque with target working angle and speed. The weight reduction of structure is carried out using optimization method after the initial design process is complete. The optimization is conducted under the load conditions of stair walking. The optimized design is validated via finite element analysis and experiments. As a result, the weight is reduced using topology and shape optimization but maintaining the safety of structure. Also the space efficiency is improved due to its compact size.

• The Journal of Korea Robotics Society
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• v.7 no.3
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• pp.171-181
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• 2012

Outdoor mobile robots are faced with various terrain types having different characteristics. To run safely and carry out the mission, mobile robot should recognize terrain types, physical and geometric characteristics and so on. It is essential to control appropriate motion for each terrain characteristics. One way to determine the terrain types is to use non-contact sensor data such as vision and laser sensor. Another way is to use contact sensor data such as slope of body, vibration and current of motor that are reaction data from the ground to the tire. In this paper, we presented experimental results on terrain classification using contact sensor data. We made a mobile robot for collecting contact sensor data and collected data from four terrains we chose for experimental terrains. Through analysis of the collecting data, we suggested a new method of terrain feature extraction considering physical characteristics and confirmed that the proposed method can classify the four terrains that we chose for experimental terrains. We can also be confirmed that terrain feature extraction method using Fast Fourier Transform (FFT) typically used in previous studies and the proposed method have similar classification performance through back propagation learning algorithm. However, both methods differ in the amount of data including terrain feature information. So we defined an index determined by the amount of terrain feature information and classification error rate. And the index can evaluate classification efficiency. We compared the results of each method through the index. The comparison showed that our method is more efficient than the existing method.

• The Journal of the Korea Contents Association
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• v.16 no.12
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• pp.327-345
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• 2016

The purpose of this study was to carry out cognitive movement therapy program for children with affective and behavioral disorder based on neuro science, psychology, motor learning, muscle physiology, biomechanics, human motion analysis, movement control and to quantify characteristic of expression and gestures according to change of facial expression by emotional change. We could observe problematic expression of children with affective disorder, and could estimate the efficiency of application of movement therapy program by the face expression change of children with affective disorder. And it could be expected to accumulate data for early detection and therapy process of development disorder applying converged measurement and analytic method for human development by quantification of emotion and behavior therapy analysis, kinematic analysis. Therefore, the result of this study could be extendedly applied to the disabled, the elderly and the sick as well as children.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.65-76
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• 1996

A screw propeller is usually accepted as a propulsor of many kinds of ships. However, for high speed vessels, screw propeller has large cavitation area on the blades so propeller efficiency is decreased and erosion can be happened. To avoid this problem, supercavitating propeller and waterjet are generally used for high speed vessels. In this paper, we introduced the self-propulsion test procedure which has been developed for high speed vessels in Hyundai Maritime Research Institute. The model ship used in experiment represents catamaran about 5.3 m in length. To minimize the experimental errors, two impellers were driven by a single motor. Thrust was calculated by converting the measured pressure to flow rates at the nozzle exit. The test procedure is composed of resistance test, self propulsion test and analysis. In order to measure the pressure, pressure tabs were installed around the nozzle exit and connected to the pressure sensor by vinyl tube.

• Physical Therapy Korea
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• v.25 no.3
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• pp.1-11
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• 2018

Background: Lumbopelvic stability is highly important for exercise therapy for patients with low back pain and shoulder dysfunction. It can be attained using a pelvic compression belt. Previous studies showed that external pelvic compression (EPC) enhances form closure by reducing sacroiliac joint laxity and selectively strengthens force closure and motor control by reducing the compensatory activity of the stabilizer. In addition, when the pelvic compression belt was placed directly on the anterior superior iliac spine, the laxity of the sacroiliac cephalic joint could be significantly reduced. Objects: This study aimed to compare the effects of EPC on lumbopelvic and shoulder muscle surface electromyography (EMG) activities during push-up plus (PUP) and deadlift (DL) exercise, trunk extensor strength during DL exercise. Methods: Thirty-eight subjects (21 men and 17 women) volunteered to participate in this study. The subjects were instructed to perform PUP and DL with and without the EPC. EMG data were collect from serratus anterior (SA), pectoralis major (PM), erector spinae (ES), and multifidus (MF). Trunk extensor strength were tested in DL exercise. The data were collected during 3 repetitions of all exercise and the mean of root mean square was used for analysis. Results: The EMG activities of the SA and PM were significantly increased in PUP with pelvic compression as compared with PUP without pelvic compression (p<.05). In DL exercise, a significant improvement in trunk extensor strength was observed during DL exercise with pelvic compression (p<.05). Conclusion: The results of this study indicate that lumbopelvic stabilization reinforced with external pelvic compression may be propitious to strengthen PUP in more-active SA and PM muscles. Applying EPC can improve the trunk extensor strength during DL exercise. Our study shows that EPC was beneficial to improve the PUP and DL exercise efficiency.