• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.146-153
• /
• 2000

The rubber crawler system for farm machine is composed of driving units such as track rollers, driving sprockets and rubber crawlers. Vibration characteristics of the rubber crawler system varies by driving speed, center of gravity, mass□moment of inertial□location arrangement of track rollers and dynamic parameters such as dynamic spring constant (k) and viscous damping coefficient (c) of a rubber crawler. In general, vibration of the rubber crawler system occurs by reason for mechanical interaction between the rubber crawler and track rollers. Because the dynamic spring constant and viscous damping coefficient vary periodically by mechanical characteristics(deformation characteristics) of the rubber crawler when track rollers drive on the between lugs of the rubber crawler. Therefore, both dynamic parameters k and c were expressed as Fourier series by authors through the shaking test of the rubber crawler and further, vibration characteristics of the rubber crawler system could be simulated analytically. However, actual values of dynamic parameters k and c are different from those obtained by the shaking test because dynamic characteristics of the rubber crawler vary by the effect of variable tension and driving resistance of track rollers. So, actual values of k and c should be identified in the condition of actual driving test. In this study, dynamic parameters such as k and c of the rubber crawler system, which are expressed as Fourier series, were identified using the Gauss-Newton Method. Therefore, validity of identified parameters k and c was discussed through the simulation using experimental data of actual driving test. As a result, in the Fourier series of dynamic parameters of spring constant k and viscous damping coefficient c, excellent parameter convergence and simulation were observed using the Fourier series' zero order and first term of the dynamic model. Furthermore, it was clarified that identification for model parameters which are fitted to actual dynamic motion (vibration) wave of the crawler system was possible by using the time series data observed in vertical and pitching motion of the crawler system.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.603-606
• /
• 2000

The cost needed for the construction and management of highways in the whole nation is rapidly growing so the research that can decrease the cost is required. However, most of the highway specs have simply converted from those of other countries, including USA. Therefore, some of our design and construction specs were not the optimum ones based on our own situation, requiring a research under the actual traffic and environment of our nation. The use of test road develops many aspects of highway engineering. Those are evaluation of construction materials, a general overview of korea pavement design and serviceability under the actual traffic and environmental condition of the nation. It is also economical and efficient compared to the trial construction of each item in spreaded form. A test road, 7.7km long with two lanes, is being constructed on the Inner Central Expressway. In this test road, 2.7km is planned for asphalt pavement and 3.4km is planned for concrete pavement. Three test bridges and five earth retaining structures will be included in the test road. Based on the master plan, the major performance was progressing such as detailed research modules of each area, preliminary research for the future research, sensor surveys for the behavior analyses of pavements and structures with installation methods and data acquisition systems, the foundation research of Integrated Instrumentation System and the Management Plan for automated measurement. Some area(structure research division, geotechnical research division) was designed the instrumentation plan because some instrument sensors must be installed during the construction of the test road. And then the instrumentation plan of each area was enforcing because a large majority of the instrument sensors must be installed after the construction of the test road. The field surveys with material property tests and pilot instrumentation test with sensor tests was also performing in accordance with the construction in the field.

• Journal of Power System Engineering
• /
• v.18 no.5
• /
• pp.144-149
• /
• 2014

The silencer of 155mm caliber howitzer is developed to reduce its firing loud noise. This kind of research of a large gun was seldom because its big firing noise does not make significant effect even if to use silencer. Nowadays, military facilities became closely located civilian residential area. The noise would be regarded environmental pollution. So the noise reducing research becomes reconsidered. The previous silencer researches were only dealt with small guns as pistols and rifles moreover their theories was not properly analyzed for a large caliber silencer. The reason was previous researches of a large caliber silencer as 155mm howitzer were limited because their data based on simulation results without actual test by using computational fluid dynamics. In this study, the entire processes of silencer of 155mm caliber howitzer which were design, manufacturing, actual firing test, and analysis of its theories, were performed and showed. In particular, the actual noise of with silencer and without was measured and the results were compared to analyze the effect of silencer.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.11
• /
• pp.1511-1515
• /
• 2001

A prediction of 305 d milk production from early records using an empirical Bayes method (EBM) was performed. The EBM was compared with the best predicted estimation (BPE), test interval method (TIM), and the linearized Wood's model (LWM). Daily milk yields were obtained from 606 first lactation Japanese Holstein cows in three herds. From each file of 305 daily records, 10 random test day records with an interval of approximately one month were taken. The accuracies of these methods were compared using the absolute difference (AD) and the standard deviation (SD) of the differences between the actual and the estimated 305 d milk production. The results showed that in the early stage of the lactation, EBM was superior in obtaining the prediction with high accuracy. When all the herds were analyzed jointly, the AD during the first 5 test day records were on average 373, 590, 917 and 1,042 kg for EBM, BPE, TIM, and LWM, respectively. Corresponding SD for EBM, BPE, TIM, and LWM were on average 488, 733, 747 and 1,605 kg. When the herds were analyzed separately, the EBM predictions retained high accuracy. When more information on the actual lactation was added to the prediction, TIM and LWM gradually achieved better accuracies. Finally, in the last period of the lactation, the accuracy of both of the methods exceeded EBM and BPM. The AD for the last 2 samples analyzing all the herds jointly were on average 141, 142, 164, and 214 kg for LWM, TIM, EBM, and BPE, respectively. In the current practices of collecting monthly records, early prediction of future milk production may be more accurate using EBM. Alternatively, if enough information of the actual lactation is accumulated, TIM may obtain better accuracy in the latter stage of lactation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.457-467
• /
• 2020

Increasing environmental concerns have prompted countries around the world to tighten regulations on greenhouse gases and fuel efficiency. Research is being done using advanced driver assistance systems to improve fuel economy and for the convenience of drivers. Research on systems such as adaptive cruise control (ACC), LKAS, and AEB is active. The purpose of ACC is to control the longitudinal speed and distance of the vehicle and minimize the driver's load, which is considered useful for accident prevention. From this point of view, research has used a mathematical method of safety evaluation as a function of distances and scenarios while considering domestic road environments. A vehicle is tested with a simulation in a proposed scenario. The purpose of the analysis is to verify the functional safety of ACC by comparing the theoretical calculations using theoretical equations, the relative distances in the simulation, and an actual vehicle test. These methods are expected to enable many companies to use scenarios, formulas, and simulations as safety verification methods in the development of ACC.

• Nuclear Engineering and Technology
• /
• v.43 no.4
• /
• pp.355-360
• /
• 2011

This paper is a study on a nuclear water chiller. It presents a test-verified finite element model of a water chiller to be used at a Nuclear Power Plant. The test-verified model predicts natural frequencies within 5% for all major modes below 50 Hz. This model accurately represents the dynamic characteristics of the actual hardware and is qualified for its use in the final stress analysis for seismic verification.

• Journal of Auto-vehicle Safety Association
• /
• v.11 no.4
• /
• pp.28-38
• /
• 2019

In the world, traffic accidents and environmental pollution caused by the increase of vehicles are becoming a serious social problem. According to the 2016 data published by the Korea Highway Traffic Authority, Korea owns 49.9 vehicles per 100 people. This is the 28th largest number among the 35 OECD member countries. In addition, the number of deaths from traffic accidents in Korea totaled 4,292, of which 1,714 were caused by traffic accidents involving vehicles and pedestrians. To reduce these human casualties, the automotive industry is constantly working on the development and commercialization of Adaptive Driver Assist System (ADAS). ADAS is the system providing convenience and safeness for drivers. In general, ADAS consists of Autonomous Emergency Braking (AEB), Highway Driving Assist (HDA), Adaptive Cruise Control (ACC), Lane Keeping Assist System (LKAS). Among them, the AEB detects the possibility of collision by the vehicle itself and plays a role of avoiding the collision or reducing the damage through active braking. For such AEB, Euro NCAP has been developing test-evaluation methods for the vulnerable since 2017. Therefore, In this paper analyzes the scenario of Euro NCAP VRU Test Protocol v3.0.1, which will be established in 2020, and proposes test conditions according to the Korean road traffic law. In addition, the reliability of the proposed scenario and test conditions was verified by comparing and analyzing the proposed theoretical evaluation formulas and actual test results.

• Journal of the Korean Institute of Gas
• /
• v.17 no.6
• /
• pp.1-7
• /
• 2013

Internal pressure variation analysis and actual holding time test on ISO LNG tank containers which were made in Korea for the first time according to the special notification of ISO tank container manufacture have been conducted during the transport demonstration projects of the tank containers by tractor, train and ship. The internal pressure of the LNG tank container increased rapidly after LNG filling and dropped during moving the container. However, it was stabilized as time passed and followed the liquid-vapor equilibrium graph. In addition, actual holding time of the tank container was more than 20 days which was satisfied with the special notification of LNG tank container manufacture.

• Journal of Fashion Business
• /
• v.10 no.1
• /
• pp.132-147
• /
• 2006

The purpose of this study is to provide for the basic data useful to the effective production and marketing of the foundation garment befitting adult women's shapes and preferences, and thereby, help them improve their apparel life. For this purpose, 563 Korean women aged between 20-59 were sampled to survey their recognition and actual wearing condition of foundation garments and positively identify the factors affecting the practices and thereupon, determine the correlations among them by age group. The raw data of this study is processed by SPSS Win(10.1) and analyzed by using frequency, percentage, $x^2$-test, ANOVA, Duncan-test. The most of adult women were aware of their foundation size and the absolute majority of them wore brassieres, while a half of them used the girdles. The adult women had 5.7 Brassieres and 2.2 Girdles. The use of the foundation depended much on user's age or seasons. They had begun to wear Brassieres at their age of 15 on an average and Girdle around their age of 19 depending their individual needs. It has been found through this study that adult women's is actual wearing condition of foundation garments differ by age group, which may well suggest that foundation production need to consideration this age-wise practices when setting up their foundation production and marketing strategies.

• Journal of the Korean Home Economics Association
• /
• v.41 no.10 s.188
• /
• pp.45-55
• /
• 2003

This study was performed to find ways to improve the wearing comfort of high school boys' summer uniforms. The subjects were 640 boy students of high schools in Cheongju and Ansung city. The data was collected self-administered questionnaires to measure the actual wearing condition and the wearing satisfaction. Factor analysis, t-test, and F-test were used for data analysis. The results were as fellows: 1) Most students were wearing shirts made of polyester/rayon blended fabrics and pants made of wool/polyester blended fabrics. 2) Most students were wearing round neckline T-shirts or running shirts as underwears of the shirts, and trunks as pants. 3) About a half of respondents had altered their summer uniforms, and main alteration of their uniforms was focused on making their pants narrow. 4) The wearing satisfaction of uniforms were classifies into three factors: aesthetic, moving function, thermal comfort wearing sensation. 5) They evaluated the wearing sensation of school uniforms of shirts and pants with low satisfaction. 6) There were partially significant differences in three factors of the wearing satisfaction according to the uniform's fabrics, the wearing of underwear and the alteration of uniform.