• Advances in nano research
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• v.14 no.2
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• pp.141-154
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• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.1
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• pp.61-72
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• 2023

The increase in the rearing intensity of pigs has caused deterioration in the pig house's internal environment such as temperature, humidity, ammonia gas, and so on. Traditionally, the widely used method to control the internal environment was through the manipulation of the ventilation system. However, the conventional ventilation system had a limitation to control the internal environment, prevent livestock disease, save energy, and reduce odor emission. To overcome this problem, the air-recirculated ventilation system was suggested. This system has a semi-closed loop ventilation type. For designing this system, it was essential to evaluate the ventilation rates considering the pressure loss of ducts. Therefore, in this study, pressure loss calculation and experiment were conducted for the quantitative ventilation design of a semi-closed loop system. The results of the experiment showed that the inlet through which external air flows should always be opened. In addition, it was also found that for the optimum design of the semi-closed loop ventilation system, it was appropriate to install a damper or a backflow prevention device rather than a ventilation fan.

• Smart Structures and Systems
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• v.32 no.5
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• pp.297-308
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• 2023

Dynamic deflection is important for evaluating the performance of a long-span cable-stayed bridge, and its continuous measurement is still cumbersome. This study proposes a dynamic deflection monitoring method for cable-stayed bridge based on Bi-directional Long Short-term Memory (BiLSTM) neural network taking advantages of the characteristics of spatial variation of cable acceleration response (CAR) and main girder deflection response (MGDR). Firstly, the relationship between the spatial and temporal variation of the CAR and the MGDR is described based on the geometric deformation of the bridge. Then a data-driven relational model based on BiLSTM neural network is established using CAR and MGDR data, and it is further used to monitor the MGDR via measuring the CAR. Finally, numerical simulations and field test are conducted to verify the proposed method. The root mean squared error (RMSE) of the numerical simulations are less than 4 while the RMSE of the field test is 1.5782, which indicate that it provides a cost-effective and convenient method for real-time deflection monitoring of cable-stayed bridges.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1528-1534
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• 2013

This paper proposes the optimal design of stator shape for cogging torque reduction of single-phase brushless DC (BLDC) motor with asymmetric notch. This method applied size and position of asymmetric notches to tapered teeth of stator for single-phase BLDC motor. Which affects the variation of the residual flux density of the permanent magnet. The process of optimal design included the extraction of the sampling point by using Latin Hypercube Sampling(LHS), and involved the creation of an approximation model by using kriging method. Also, the optimum point of the design variables were discovered by using the Genetic Algorithm(GA). Finite element analysis was used to calculate the characteristics analysis and cogging torque. As a result of finite element analysis, cogging torque were reduced approximately 39.2% lower than initial model. Also experimental result were approximately 38.5% lower than initial model. The period and magnitude of the cogging torque were similar to the results of FEA.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.205-213
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• 1988

It is not a simple task to optimize a cable stayed bridge, because it involves, in addition to the section properties, number and arrangement of cables, initial tension forces of cables, and type and height of the tower as design variables. This study deals with an optimization problem of cable stayed bridges considering initial cable forces, section properties of the girder and the tower, and coordinates of the tower. In order to avoid difficulties in dealing with numerous variables which interact mutually, separate design spaces are adopted for initial cable forces, section properties, and coordinates, respectively. Strain energy stored in the structure is used as the object function in the design of the initial cable forces, while weight of the structure is used in the design of section and coordinates. Upper and lower limits of the initial forces, allowable stresses including the effect of buckling, and lower limit of the sectional area are considered as constraints. The proposed method is applied to a fan type bridge and a harp type bridge. It is believed through comparison of the results to the previous results in the literature that the proposed method renders rational design values. It is also shown that the coordinate optimization, which is usually deleted in the optimization process, results in additional saving of materials.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.782-795
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• 2019

Safety is always acritical focus of exploration of ocean resources, and it is well recognized that human factor is one of the major causes of accidents and breakdowns. Our research developed a dynamic human reliability assessment approach, Predicted Mean Vote-Cognitive Reliability and Error Analysis Method (PMV-CREAM), that is applicable to monitoring the cognitive reliability of oceanauts during deep-sea missions. Taking into account the difficult and variable operating environment of manned submersibles, this paper analyzed the cognitive actions of oceanauts during the various procedures required by deep-sea missions, and calculated the PMV index using human factors and dynamic environmental data. The Cognitive Failure Probabilities (CFP) were calculated using the extended CREAM approach. Finally, the CFP were corrected using the PMV index. This PMV-CREAM hybrid model can be utilized to avoid human error in deep-sea research, thereby preventing injury and loss of life during undersea work. This paper verified the method with "Jiaolong" manned submersible 7,000 m dive test. The"Jiaolong" oceanauts CR(Corrected CFP) is dynamic from 3.0615E-3 to 4.2948E-3, the CR caused by the environment is 1.2333E-3. The result shown the PMV-CREAM method could describe the dynamic human reliability of manned submersible caused by thermal environment.

• Journal of the Korea Fashion and Costume Design Association
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• v.9 no.3
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• pp.181-189
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• 2007

This study aims to conduct research into the property of costumeplay that has been established with our unique characteristics despite the critics from the existing generation, and the cospre style preferred by costumeplayers. The research methods include literature study, existing research, and a survey targeting costumeplayers who make costumes upon order or borrow costumes on websites. The findings are as follows. 1. From the results of the survey, 77% of the participants in the costumeplay were secondary school students, 16% were college students, and 5% were primary school students. 2. The distribution of the residences of the costumeplayers was found to be mostly centered in two areas including Seoul/Gyeonggi and Gyeongsang/Busan, which were 39% and 37% each. This is probably because Seoul Comic and Busan Comic were regularly taking place, and these are relatively economically affluent areas and locations where the rapid exchange of Japanese culture occurs. 3. For the cospre style preferred by costumeplayers, 57% of respondents preferred costumes for reviving characters, 18% of them for fan-cospre and 14% of them for reviving a character and creating new characters. Costumeplayers preferred cospre costumes for reviving characters rather than for creating new characters. 4. Most respondents preferred a character-oriented design, posting 31.9%. Next, 17.5% of them selected the Lolita look This is probably because the Lolita look which is much favored in the latest fashion trends affects them, and the rest of the respondents preferred a fantasy/SF group, visual, uniform, and maid look, in order. 5. For costs required for costumeplay for 1 time, 39% of respondents spent about KRW $100,000{\sim}150,000$, and 24% of them about KRW $150,000{\sim}200,000$. However, for buying accessories or small items, over 50% of them spent KRW $30,000{\sim}40,000$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.219-224
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• 2012

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate jet turbofan engine named BR715-56 which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.280-292
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• 2019

This study was carried out for the Centum Shinsegae Department Store, to grasp the indoor rest space and furniture design status, this study analyzes the characteristics of visitors' use behavior centered on furniture. The purpose of this study is to provide basic data for commercial rest space design by understanding the characteristics of resting space in commercial space and whether the furniture can support the behavior of visitors. The research method is to carry out on-site inspection, including the location of the rest space on each floor, the type and design characteristics of the furniture design, and the characteristics and patterns of the users on each were analyzed. The results of the study are as follows. As a result of analyzing the rest space and furniture, the furniture is brown, it has been provided with various designs such as fan-shaped, arched bench, sofa, chair type, and comfortable colors of lightness ranging from light gray to black, and appropriately supported the most common usage patterns.However, in the case of Shinsegae Department Store, it is necessary to consider the safety and convenience of the vulnerable groups.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.421-426
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• 2018

This study is meant to derive what is needed to enhance the convenience and satisfaction of users of mobile credit card applications. For the first step, the current status of simple payment service using application has been identified and in-depth interview by reorganizing Peter Morvile's Honeycomb model into the five usage principle based on the main function of the application card. As a result, it was found that users prefer personalized services that fulfill the purpose and key functions of the app card and take into account their consumption patterns rather than too many additional functions. Based on this study, it is expected that it would help card companies increase their experience with app card users and strengthen their platforms.