• Journal of Biosystems Engineering
• /
• v.29 no.2
• /
• pp.101-108
• /
• 2004

The objectives of this study were to determine the natural frequency of a walking-type cultivator's handle using a modal analysis, to determine whether or not the handle resonates with forcing frequency induced by its engine, and to determine a method to reduce the handle vibration using a technique of the operational deflection shapes(ODS). Results of the study are as follows: The natural frequencies of the handle up to third harmonics were found to be 20.4, 22.5 and 92.1 Hz in the vertical direction and 14.9, 93, and 132 Hz in the horizontal direction. It was found that the handle does not resonate with the forcing frequency of the engine, which is 52 Hz. The operational deflection shape analysis revealed the deflected shapes of the handle in the vertical and horizontal directions and suggested that the handle vibration can be reduced by adding some mass to the place where the largest deflection occurs. Attaching of 1.1 kg mass adjacent to the largely deflected area resulted in reductions of vibration from 9.45 to 8.03 m/s$^2$ in x-axis direction from 3.89 to 3.16 m/s$^2$ in y-axis direction and from 7.89 to 3.09 m/s$^2$ in z-axis direction, which are respectively 15, 19 and 61% reductions. The total vibration level was reduced by 29%, indicating that mass-adding method by the ODS is very effective for reducing the handle vibrations of the cultivators.

• Steel and Composite Structures
• /
• v.16 no.1
• /
• pp.21-44
• /
• 2014

The aim of this study is to determine the dynamic characteristics of long reinforced concrete highway bridges with post-tension tendons using analytical and experimental methods. It is known that the deck length and height of bridges are affected the dynamic characteristics considerably. For this purpose, Berta Bridge constructed in deep valley, in Artvin, Turkey, is selected as an application. The Bridge has two piers with height of 109.245 m and 85.193 m, and the total length of deck is 340.0 m. Analytical and experimental studies are carried out on Berta Bridge which was built in accordance with the balanced cantilever method. Finite Element Method (FEM) and Operational Modal Analysis (OMA) which considers ambient vibration data were used in analytical and experimental studies, respectively. Finite element model of the bridge is created by using SAP2000 program to obtain analytical dynamic characteristics such as the natural frequencies and mode shapes. The ambient vibration tests are performed using Operational Modal Analysis under wind and human loads. Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) methods are used to obtain experimental dynamic characteristics like natural frequencies, mode shapes and damping ratios. At the end of the study, analytical and experimental dynamic characteristic are compared with each other and the finite element model of the bridge was updated considering the material properties and boundary conditions. It is emphasized that Operational Modal Analysis method based on the ambient vibrations can be used safely to determine the dynamic characteristics, to update the finite element models, and to monitor the structural health of long reinforced concrete highway bridges constructed with the balanced cantilever method.

• Journal of Information Technology Services
• /
• v.18 no.4
• /
• pp.67-82
• /
• 2019

The purpose of this study is to improve the calculation method of the software operation pricing proposed by the software business price calculation guide from 'input manpower method' to 'rate calculation method'. The software operation pricing of the input manpower method is not objectively calculated in the domestic IT outsourcing situation where the statistical data based on the activity based estimating is insufficient and it is decided by agreement between the owner and the client. In addition, there was no standard for adjusting the productivity according to the characteristics of the operation service. In order to improve this, an operational correction factor item that can affect the software operation productivity was selected based on foreign and domestic standards, and it was confirmed through the first questionnaire to IT operation managers. In order to determine the level of difficulty of the fixed operational correction factors, the operational correction factor using AHP technique was confirmed through a second questionnaire for pairwise comparison. The operational difficulty calculation table was developed with reference to COCOMO and ITIL standards. Finally, we propose a new pricing scheme that reflects the operating rate. Regression analysis was carried out by collecting the data of the domestic public institutions on the estimated cost and the actual cost calculated from the new rate method software operation pricing. The results of the regression analysis show that the estimated cost and the actual cost are related to each other. Mean magnitude of relative error(MMRE) and PRED[25] analysis were added for accuracy analysis. MMRE and PRED also showed satisfactory results, confirming the possibility of replacing the rate method software operation pricing.

• Journal of the Korea Society for Simulation
• /
• v.19 no.2
• /
• pp.63-72
• /
• 2010

In the future warfare, the importance of the counter-fire operation is increasing. The counter-fire operation is divided into offensive counter-fire operation and defensive counter-fire operation. Reviewing the researches done so far, the detection asset of offensive counter-fire operation called UAV(Unmanned Aerial Vehicle) and its operational effectiveness analysis is continually progressing. However, the analysis of the detection asset of defensive counterfire called Target Acquisition Radar(TAR) and its quantitative operational effectiveness are not studied yet. Therefore, in this paper, we studied operational effectiveness of TAR using C2 Theory & MANA Simulation model, and showed clear quantitative analysis results by comparing both cases of using TAR and not using TAR.

• Atmosphere
• /
• v.32 no.1
• /
• pp.71-84
• /
• 2022

This paper describes verification results for the ocean analysis field produced by the Nucleus for European Modelling of the Ocean (NEMO) of the Korea Meteorological Administration (KMA) against observed Argo floats and drift buoys over the western Pacific Ocean and the equatorial Pacific during 2020~2021. This is confirmed by a comparison of the verification for the newly updated version of the HYbrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation (HYCOM/NCODA) against same observations. NEMO shows that the vertical ocean temperature is much closer to the Argo floats than HYCOM for most seasons in terms of bias and root mean square error. On the other hand, there are overall considerable cold biases for HYCOM, which may be due to the more rapid decreasing temperature at the shallow thermocline in HYCOM. Conclusion demonstrated that the NEMO analysis for ocean temperature is more reliable than the analysis produced by the latest version of HYCOM as well as by the out-of-date HYCOM applied to the precedent study. The surface ocean current produced by NEMO also shows 14% closer to the AOML (Atlantic Oceanographic and Meteorological Laboratory) in situ drift buoys observations than HYCOM over the western Pacific Ocean. Over the equatorial Pacific, however, HYCOM shows slightly closer to AOML observation than NEMO in some seasons. Overall, this study suggests that the resulting information may be used to promote more use of NEMO analysis.

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.5
• /
• pp.405-410
• /
• 2017

This paper deals with 3D simulation of industrial robot for automated manufacturing system. In order to evaluate the operational characteristics of the industrial robot system in the worst case motion scenario, flexible - rigid multibody analysis was performed. Then, the rigid body dynamics analysis was performed and the results were compared with the flexible - rigid multibody analysis. Modal analysis was also performed to confirm the dynamic characteristics of the robot system. In the case of the flexible-rigid multibody simulation, only the structural members of interest were modeled as elastic bodies to confirm the stress state. The remaining structural members were modeled as rigid bodies to reduce computer resources.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.5
• /
• pp.660-666
• /
• 2012

The weapon system is getting more and more expensive, complex and smarter. Therefore, efficiently and effectively, it is important to operate the weapon system. OMS/MP is a document to quantify operational factors like as environment, mission, mode etc. It is important data to perform RAM analysis in early weapon development phase and operate better a weapon system. This paper present a process and framework of OMS/MP for a naval ship with a deep analysis of relevant domestic and abroad case studies. It propose OMS/MP analysis framework based on wartime scenario and mission area analysis. This result will contribute not only improvement for the availability of a naval ship but also enhancement of RAM analysis process.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.12
• /
• pp.1090-1097
• /
• 2000

Predicting building energy use can be useful to evaluate its energy performance. This study proposed empirical approach for predicting building energy use with regression analysis. For the empirical analysis, simple regression models were developed based on the historical energy consumption data as a function of daily outside temperature, the predicting equations were derived for different operational modes and day types, then the equations were applied for predicting energy use in a building. BY selecting a real building as a case study, the feasibilities of the empirical approach for predicting building energy use were examined. The results showed that empirical approach with regression analysis was fairly reliable by demonstrating prediction accuracy of $pm10%$ compared with the actual energy consumption data. It was also verified that the prediction by regression models could be simple and fairly accurate. Thus, it is anticipated that the empirical approach will be useful and reliable tool for many purposes: retrofit savings analysis by estimating energy usage in an existing building or the diagnosis of the building operational problems with real time analysis.

• Journal of Service Research and Studies
• /
• v.11 no.4
• /
• pp.43-55
• /
• 2021

This study analyzed the efficiency of medical services in OECD member countries by dividing it into operational efficiency and quality efficiency. For this purpose, data from 2017-2019 OECD Health Statistics were used. As the analysis method, super efficiency was measured by applying an output-oriented Variable Returns to Scale (VRS) model. As a result of the analysis, Switzerland, Korea, and Italy were included in the high group of operational efficiency, Canada, Greece, Denmark, etc. in the medium group, and Belgium, Germany, and Spain in the low group. Based on quality efficiency, Norway, Switzerland, and Spain are in the high group, and Greece, Denmark, Mexico, etc. are in the medium group, and the Netherlands, Germany, Belgium, etc. were included in the low group. As a result of comparative analysis of efficiency by OECD member countries as of 2018, it was found that Korea's operational efficiency was the most efficient and quality efficiency was inefficient. Korea (0.998) should improve life expectancy by 0.2 (0.2%) and subjective health perception by 44.2 (138.1%) by benchmarking Greece (0.422), Switzerland (0.207), and Spain (0.371) to improve quality efficiency. Unlike most previous studies that focused on operational efficiency, this study measured quality efficiency together and analyzed the efficiency of the medical service industry in each OECD member country. Through this, this study has implications in that it confirmed the international competitiveness of the domestic medical service industry and suggested ways to improve efficiency.

• The KIPS Transactions:PartD
• /
• v.14D no.6
• /
• pp.689-700
• /
• 2007

Organizations and customers lose if business activities we discontinued by an incident of information systems under the current business environment because they pursue real time enterprise and on demand enterprise. The loss includes the intangible decline in brand image, customer separation, and the tangible loss such as decrease in business profits. Thus. it is necessary to have preparedness in advance and mitigation for minimization of a loss due to the business discontinuity and information system's operational risks. This paper suggests the mitigation model for minimizing the incidents of disk unit in information system's operational risks. The model will be represented by a network model which is composed of the three items as following: (1) causes, attributes, indicators of an operational risk, (2) a periodic time through an analysis of historical data, (3) an index or a regulation related to the examination of causes of an operational risk.