• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.489-494
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• 2014

Estimation of correct ice load under various operating conditions is important during the design and the operation stages of an icebreaker. Normal operating conditions are expected from the official field ice trials and also from general ice transit action. In this paper ice load for the Korean icebreaking research vessel, ARAON, under normal operating condition, is discussed. Published ice load data from full-scale sea trials of six icebreakers were analysed to derive an empirical ice load prediction formula. The IBRV ARAON had sea ice trials during 2010 and 2012 summer season. Strain gauge signal were recorded during her icebreaking voyage and the measured strain data were converted to the equivalent hull stress values. The effect of ARAON's speed in ice and the hull stresses are investigated. By comparing the empirical formula and ice load calculation based von measured data, it is recommended to use the empirical ice load estimation formula for the initial design stage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.128-136
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• 2008

It is necessary to estimate the cooling load of the next day for effective control of ice thermal storage system. In this paper, new methodology is proposed to estimate the cooling load using design parameters of building and predicted weather data. Only six input parameters such as sensible heat coefficient and constant, latent heat coefficient and constant, maximum and minimum temperature are necessary to obtain hourly distribution of cooling load for the next day. Two benchmarking buildings(hospital and research institute) are selected to validate the performance of the proposed method, and the estimated cooling loads in hourly and daily bases are calculated and compared with the measured data for E hospital. The estimated results show fairly good agreement with the measured data for both buildings.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.70-78
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• 2018

Due to the increasing concern about climate change, efforts to reduce environmental load are continuously being made in construction industry, and life cycle assessment (LCA) is being presented as an effective method to assess environmental load. Since LCA requires information on construction quantity used for environmental load estimation, however, it is not being utilized in the environmental review at the initial design stage where it is difficult to obtain such information. In this study, a construction quantity computation system based on the standard section was developed for the drainage facilities of the road and utilized in the model to calculate the environmental load. This model can estimate the environmental load by calculating the amount of resources required for LCA using only the information available at the initial design stage. To verify the validity of the model, five validation cases were applied and compared with the unit estimation model and the multiple regression analysis model. As a result, it is confirmed that the mean absolute error rate is 9.94%, which is relatively accurate and effective model in the initial design stage.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.326-330
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• 2001

A nonlinear speed control for a permanent magnet (PM) synchronous motor using a simple disturbance estimation technique is presented. By using a feedback linearization, scheme, the nonlinear motor model can be linearized. To compensate an undesirable output performance under the mismatch of the system parameters and load conditions the controller parameters will be estimated by using a disturbance observer theory. Since only the two reduced-order observers are used for the parameter estimation, the observer designs are considerably simple and the computational load of the controller for parameter estimation is negligibly small. The proposed control scheme is implemented on a PM synchronous motor using DSP TMS320C31 and the effectiveness is verified through the comparative experiments.

• Wind and Structures
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• v.36 no.4
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• pp.221-236
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• 2023

The lateral component of turbulence and the vortices shed in the wake of a structure result in introducing dynamic wind load in the acrosswind direction and the resulting level of motion is typically larger than the corresponding alongwind motion for a dynamically sensitive structure. The underlying source mechanisms of the acrosswind load may be classified into motion-induced, buffeting, and Strouhal components. This study proposes a frequency domain framework to decompose the overall load into these components based on output-only measurements from wind tunnel experiments or full-scale measurements. First, the total acrosswind load is identified based on measured acceleration response by solving the inverse problem using the Kalman filter technique. The decomposition of the combined load is then performed by modeling each load component in terms of a Bayesian filtering scheme. More specifically, the decomposition and the estimation of the model parameters are accomplished using the unscented Kalman filter in the frequency domain. An aeroelastic wind tunnel experiment involving a tall circular cylinder was carried out for the validation of the proposed framework. The contribution of each load component to the acrosswind response is assessed by re-analyzing the system with the decomposed components. Through comparison of the measured and the re-analyzed response, it is demonstrated that the proposed framework effectively decomposes the total acrosswind load into components and sheds light on the overall underlying mechanism of the acrosswind load and attendant structural response. The delineation of these load components and their subsequent modeling and control may become increasingly important as tall slender buildings of the prismatic cross-section that are highly sensitive to the acrosswind load effects are increasingly being built in major metropolises.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.531-537
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• 2017

The biologic Oxygen Demand (BOD) is a reliable and generally accepted indicator of water pollution by organic pollutants. Accordingly, estimation of BOD export from paddies carries important implications fwith regard to water management in rural areas. In this study, hydrology and BOD concentration were monitored during the period 2008 through 2012, in an effort to understand the characteristics of BOD export from paddy fields. The findings demonstrated that BOD load by rainfall above 50 mm. occupied about 50 % of total load, whereas the load by less than ten mm. rainfall occupied about 29 % of the total load during periods of stormy activity. It therefore seems that it could be possible to reduce the BOD load up to 29 % during storm periods, when drainage control conducted for rainfall less than ten mm.(an amount which is relatively easy to manage). The documented mean loads of storm and non-storm were $17.1kg\;ha^{-1}\;yr^{-1}$ and $11.2kg\;ha^{-1}\;yr^{-1}$, respectively. The BOD load during the significant rainfall period was similar to the renewed unit load by NIER (2014). However, there were substantial differences between unit load and actual load when the non-storm load was incorporated into the BOD load estimation from paddy fields. In view of the foregoing, it is felt that, the non-storm load needs to be further considered and managed for the successful implementation of Total Maximum Daily Load (TMDL) program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.614-617
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• 1995

The unbalance heavy-load elevation driving systems are composed of rotating link-mechanism and hydraulic cylinder which actuates elevation and compensates the static unbalance moment of supporting mechanism. Control and compensation of gun driving is very difficult because these mechanism imply highly nonlinearities due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of manufactured link-mechanism, the optimal link-mechanism design of the elevating system is suggested. Also to estimate the control performance of the unbalance heavy-load elevation servo-control driving system, modeling and simulation of the system are carried out. To prove the reliability of performance estimation program,simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the control performance improvement of the system.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.345-349
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• 1991

The accurate simulation of the static and/or dynamic response of a power system requires detailed knowledge of the behavior of the loads. For the Precise load model, the chearacteristics and the composition of the load are needed. In this papers, the reliable estimation method of load composition is suggested intruducing knowledge-based system though it used various weekly-reliable survey data.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.385-390
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• 2001

This paper presents a nonlinear analysis technique with slip, the effects of slip modulus and composite action by shear connector on behavior and capacity in composite structure of sandwich system. As a results of this study, it proved that the slip modulus, in case of shear behavior, seldom influence load-resistance capacity such as yield and ultimate load, but in case of flexural behavior, it appropriately influence load-resistance capacity because of stress redistribution by slip. In case of flexural behavior, analysis result for perfect-composite results in over-estimation and perfect-slip results in under-estimation on behavior and capacity. Therefore, it is desirable to model steel-concrete interface with partial-composite. The effects of slip on behavior and capacity are less in case of positive composite than loosely composite, and it proved that composite action by shear connector improve the load-resistance capacity of this system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.848-853
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• 2007

This paper presents a methodology of estimating incomplete information in electricity markets for analyzing the gaming behavior of Generating Companies (GENCOs). Each GENCO needs to model its opponents' unknown information of strategic biddings and cost functions. In electricity markets with complete information, each GENCO knows its rivals' payoff functions and tries to maximize its own profit at Nash equilibriurnl Nli) by acknowledging the rivals' cost function. On the other hand, in the incomplete information markets, each GENCO lacks information about its rivals. Load patterns can change continuously due to many factors such as weather, price, contingency, etc. In this paper, we propose the method of the estimation of the opponents' cost function using market price, transaction quantities. and customer load patterns. A numerical example with two GENCOs is illustrated to show the basic idea and effectiveness of the proposed methodology.