• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.146-153
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• 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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.603-606
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• 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.

• 동력기계공학회지
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• 제18권5호
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• pp.144-149
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• 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
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• 제14권11호
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• pp.1511-1515
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• 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.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.457-467
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• 2020

세계적으로 환경문제에 관한 우려가 급증하여, 세계 각국이 온실가스 연비 규제를 강화하고 있다. 연비향상을 위해 첨단 운전자 지원 시스템을 이용한 연구를 통하여, 운전자의 편의를 위해 다양한 첨단 운전자 지원 시스템을 개발하고 있다. 그중 ACC, LKAS, AEB 등의 시스템에 대한 연구가 활발하다. ACC의 목적은 차량의 종 방향 속도와 거리를 제어하고 운전자의 부하를 최소화하여 사고 예방과 방지에 유용한 시스템으로 평가되고 있다. 이러한 관점에서 본 논문은 선행연구에서 제안한 국내도로 환경을 고려한 시나리오와 거리에 대한 함수로 안전성을 평가할 수 있는 수학적 방법을 활용한다. 또한, 제안한 시나리오를 기반으로 시뮬레이션과 실도로 실차시험을 진행한 뒤, 이론수식을 활용한 이론 계산값, 시뮬레이션과 실도로 실차시험의 상대거리의 비교분석을 통하여 ACC의 기능적인 안전성을 검증하고자 한다. 이러한 방법을 통하여 많은 회사들이 ACC의 개발 단계에서 시나리오, 수식, 시뮬레이션을 활용하여 안전성 평가방법으로 활용할 수 있을 것으로 예상된다.

• 한국분무공학회지
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• 제29권2호
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• pp.68-74
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• 2024

As awareness of environmental pollution problems increases worldwide, interest in air pollutants is increasing. In particular, NOx and PM, which are major pollutants in diesel vehicles, are contributing significantly to emissions. As a result, its importance is increasing. In this study, based on research results applied to large diesel vehicles, the problem of natural regeneration caused by low exhaust gas temperature during low speed and low load operation is solved by applying a complex regeneration DPF that is not affected by temperature conditions to small diesel vehicles. The feasibility of application to small diesel vehicles was reviewed by measuring the emission reduction efficiency. As a result of the engine test, the power reduction rate and fuel consumption rate before and after device installation under full load conditions were 2.9% decrease and 3.5% increase, respectively, satisfying the standard for a 5% reduction, and as a result of the regeneration equilibrium temperature (BPT) test, the regeneration temperature was 310℃. appeared at the level. The reduction efficiency test results for the actual vehicle durability test equipment showed 97.3% PM, 51.0% CO, and 31.1% HC, while the city commuter vehicle had PM 97.5%, CO 61.7%, HC 40.0%, and the school bus vehicle had PM 96.8%, CO 44.4%, HC 34.3%, and low-speed logistics vehicles showed a reduction efficiency of 98.2% for PM, 36.0% for CO, and 45.7% for HC. Based on the results of this study, in the future, it is necessary to secure DPF technology suitable for all vehicle types through actual vehicle application research on temperature condition-insensitive composite regenerative DPF for medium-sized vehicles.

• Nuclear Engineering and Technology
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• 제43권4호
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• pp.355-360
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• 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.

• 자동차안전학회지
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• 제11권4호
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• pp.28-38
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• 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.

• 한국가스학회지
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• 제17권6호
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• pp.1-7
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• 2013

이 논문에서는 특례기준에 따라 국내에서 최초로 제작하고 검사한 LNG 탱크 컨테이너를 이용하여 육상 및 해상 운송 시연사업을 하고, 탱크 컨테이너를 운송할 때 탱크 컨테이너 내부에 충전된 LNG의 압력변화와 탱크 컨테이너의 실제 압력유지기간을 측정하였다. 탱크 컨테이너 내부의 압력은 충전 직후에는 급속하게 상승하고, 탱크 컨테이너를 이동할 때 급속히 하강하나, 일정시간이 경과한 후에는 기액평형상태 그래프의 온도-압력 변화와 일치함을 확인하였다. 또한, 탱크 컨테이너의 실제 압력유지기간은 특례기준에서 규정한 20일 이상을 만족함을 확인하였다.

• 패션비즈니스
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• 제10권1호
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• pp.132-147
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• 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.