• Journal of Power System Engineering
• /
• v.14 no.4
• /
• pp.5-10
• /
• 2010

This study was investigated the effect on operating characteristics of apparatus according to frosting and defrosting to develop of new defrosting equipment. The results showed as following. Frost was almost removed using the defrosting equipment with roll brush type that defrosting is possible under operating condition. Also, the temperature of compressor inlet, evaporator inlet and outlet showed higher value because of heat transfer resistance of cooling pipe frost comparing with defrosting condition. And the compressor work showed 10% lower and COP was presented 24% higher values than defrosting condition. Therefore, defrosting for cooling coil of refrigeration and low temperature storage was effected on operation and performance characteristics of equipment. This highly effects on real refrigeration apparatus which is operated in year-around.

• IE interfaces
• /
• v.10 no.3
• /
• pp.145-153
• /
• 1997

This paper deals with constructing a scheduling system for a mold manufacturing factory. The scheduling system is composed of 4 submodules such as pre-processor, neural network training, neural networks and simulation. Pre-processor analyzes the condition of workshop and generates input data to neural networks. Network training module is performed by using the condition of workshop, performance measures, and dispatching rules. Neural networks module presents the most optimized dispatching rule, based on previous training data according to the current condition of workshop. Simulation module predicts the earliest completion date of a mold by forward scheduling with the presented dispatching rules, and suggests a possible issue date of a material by backward tracking. The system developed shows a great potential when applied in real mold factory for automotive parts.

• Proceedings of the IEEK Conference
• /
• 2009.05a
• /
• pp.347-349
• /
• 2009

Air quality of indoor space environment is affected by various pollutants like as particles and chemical stuffs. The indoor air pollution affects directly the human respiration organs to cause consequently unpleasant mental status. The $CO_2$ concentration level is one of the harmful components of air pollutants. Major factor to increase the $CO_2$ concentration level is the people's breath amount in indoor. The car exhaust gas diffused from the around road also has strong affect on $CO_2$ concentration. There are some other reasons to affect the $CO_2$ concentration change, such as, real-time change of the population movement, closeness to the indoor air flow inlet window and changes in road car traffic amount. A remote monitoring system to measure environmental indoor air pollution concerning on the $CO_2$ concentration was studied and installed realized set-up model. Zigbee network configuration was applied for this system and the $CO_2$ concentration data were collected through USN network. A software program was developed to assure systematic analysis and to display real-time data on web pages. For the experimental test various condition was set up, like as, window opening, stopping air condition operation and adjusting fan heater work, etc. The analysis result showed the relation of various environmental conditions to $CO_2$ concentration changes. The causes to increase $CO_2$ concentration were experimentally defined as windows closing, the stopping air condition system, fan heater operation. To keep the $CO_2$ concentration under the legally required ppm level in public access indoor space, the developed remote measurement system will be usefully applied.

• Journal of the Korea Convergence Society
• /
• v.11 no.5
• /
• pp.175-182
• /
• 2020

The calculation of the optimal trajectory of the stepped top-down robot was made using a genetic algorithm and a computational torque controller. First, the total energy efficiency was minimized using the Red-Cold Generic Algorithm (RCGA) consisting of reproductive, cross, and mutation. The reproducibility condition related to the position assembly of the start and end of the stride and the joints, angles, and angular velocities are linear constraints. Next, the unequal constraint accompanies the condition for preventing the collision of the swing leg at the corner with the outer surface of the stairs, the condition of the knee joint for preventing kinematic peculiarity, and the condition of no moment in safety in the traveling direction. Finally, the angular trajectory of each joint is defined by fourth-order polynomial whose coefficient is to approximate chromosomes. This is to approximate walking. In this study, the energy efficiency of the optimal trajectory was analyzed by computer simulation through a biped robot with seven degrees of freedom composed of seven links.

• Journal of Biomedical Engineering Research
• /
• v.28 no.3
• /
• pp.369-376
• /
• 2007

With the convergence of ubiquitous networking and medical technologies, ubiquitous healthcare(U-Healthcare) service has come in our life, which enables a patient to receive medical services at anytime and anywhere. In the u-Healthcare environment, intelligent real-time biosignal aquisition/analysis techniques are inevitable. In this study, we propose a motion artifact cancelation method in portable photoplethysmography(PPG) signal aquisition using an accelerometer and an adaptive filter. A preliminary experiment represented that the component of the pedestrian motion artifact can be found under 5Hz in the spectral analysis. Therefore, we collected PPG signals under both simulated conditions with a motor that generates circular motion with uniform velocity (from 1 to 5Hz) and a real walking condition. We then reduced the motion artifact using a recursive least square adaptive filter which takes the accelerometer output as a noise reference. The results showed that the adaptive filter can remove the motion artifact effectively and recover peak points in PPG signals, which represents our method can be useful to detect heart rate in real walking condition.

• Korean Journal of Applied Biomechanics
• /
• v.29 no.1
• /
• pp.1-8
• /
• 2019

Objective: The purpose of this study was to confirm that the cross-country ski sprint course in PyeongChang, where the 2018 Winter Olympics course was to utilize wearable devices equipped with inertial measurement unit (IMU), global positioning system (GPS) and heart rates sensor. Method: For the data collection, two national level cross-country (XC) skiers performed classic technique on the entire sprint course. We analyzed cycle characteristics, range of motion on double poling (DP) technique, average velocity, and displacement of 3 points according to the terrain. Results: The absolute cycle time gradually decreased during starting, middle and finish sections. While the length of the DP increased and the heart rates tended to increase for men skier. In addition, the results indicated that range of motion of knee joint during starting and finish section decreased more than middle section. The errors of latitude and longitude data collected through GPS were within 3 m from 3 points. Conclusion: Through the first case study in Korea, which analyzed the location and condition of XC skiers in the entire sprint course in real time, confirmed that feedback was available in the field using various wearable sensors.

• Journal of Korean Society of Transportation
• /
• v.6 no.1
• /
• pp.55-64
• /
• 1988

Prior to using any computer model, the program-embedded palameters showing significant differences from real world should be calibrated. This is especially true when the model is expected to be used fro various roadway and traffic condition. The calibration of TRANSYT model was conducted for the parameters of start-up delay, and lag, stop penalty(K), platoon dispersion factor, and saturation flow rate. The values of the parameters were obtained by theoretical methods from actual field measurements for discharging and arrival pattern. The sites elected for the study was an intersection of Dongil-Ro and Hwarang-Ro, and a 334 meter downstrean section from the intersection stop line on westbound Hwarang-Ro. The study results showed that the start-up delay was 2.6 sec, end lag was 1.0 sec, saturation flow rate was 2287 pcphgpl, platoon dispersion factor was 0.2-03, and stop penalty(K) was 32. However, since these parameters re apt to depend on traffic and roadway condition, it is doubtful whether the obtained values will be applicable to the area-wide situation other than this particular site.

• Korean Journal of Human Ecology
• /
• v.12 no.5
• /
• pp.619-634
• /
• 2003

The purpose of this study was to the real situation of the safety education in the kindergarten by investigating the actual condition of the safety education and kindergarten teachers' knowledge about it. Questionnaire was adopted to obtain data required for pertinent analysis. The subjects were 234 kindergarten teachers located in Choongnam and Daejeon province. SPSSWIN v10.0 was utilized to calculate percentage, mean and standard deviation and to conduct t-test, one-way ANOVA and Duncan's multiple range test. The main results of this study were as follows. There was a significant difference between the actual condition of the safety education and kindergarten teachers' knowledge about it according to demographic variables. Especially, these differences were due to teachers' academic career, age, teaching experience, and the experience of bringing up children by themselves. The importance of the safety education must be emphasized. There were urgent needs to develop the way of teaching and the program about the safety education.

• Journal of Power System Engineering
• /
• v.11 no.1
• /
• pp.39-44
• /
• 2007

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• The Journal of the Korea Contents Association
• /
• v.12 no.9
• /
• pp.500-511
• /
• 2012

Recently, use frequency for traffic information which provides shortest paths and traffic condition is increasing. Specially, in the survey, it is shown that users prefer internet portal sites which can be used the most easily among traffic information media. But, there are not many verification systems for traffic information contents of internet portal sites which collect and provide information than traffic information contents which are provided by public service. The purpose of this study is to investigate real accuracy and accuracy felt by users about information provided by portal sites. Therefore, in this research we verified accuracy of information by portal site with real field data and investigate real usage about contents and experienced accuracy by users through survey. Also, users' expectation and satisfaction were surveyed and the contents to be improved were selected by using IPA technique. By the result of accuracy verification by field data using portable DSRC(Dedicated Short Range Communication) devices, it is shown that average error was 14~32% and sometimes very high rate. Also, it is shown that 28.3 % of total respondents prefers the information by portal sites and 50 % of total respondents felt that contents of traffic information by portal sites are not accurate. Real-time traffic condition was selected as the most inaccurate one among all contents of traffic information and it was analyzed that intensive efforts for improving information about real-time traffic condition are needed.