• Journal of The Korean Association For Science Education
• /
• v.35 no.2
• /
• pp.217-229
• /
• 2015

In this study, we explored the development of scientific model through the social-construction process on "combustion." Students were 8th graders from one middle school class. Each student engaged in small group discussions three times and made a group model on combustion. Discourses between peers and teacher were videotaped, audiotaped, and transcribed. The results show that the small groups constructed an initial concept: 'Conditions of combustion', which they then evaluated and revised the initial concept through combustion experiment. Following the discussions, some small groups evaluated their model and made a revised model. Then, the small groups compared various models and constructed a scientific model through consensus within the small group and as a whole class. Finally, students kept revising their model to 'Burning needs oxygen.' This tells us that the social construction process of scientific model made a meaningful role to build scientific model through diverse discussion between the students and their teacher, although they have had some difficult process to reach the final consensus. The data also showed some group features: the members were open to other's ideas. They analyzed the differences between their own ideas from others and revised their model after the whole class discussion. Lastly, they showed the tendency to make a good use of teacher's guidance. This study implies the importance of having social interaction process for students to understand the scientific model and learn the nature of scientific inquiry in class.

• Geomechanics and Engineering
• /
• v.33 no.6
• /
• pp.583-596
• /
• 2023

The interlayers, either softer or stiffer than the surrounding layers, are usually overlooked during field investigation due to the small thickness. They may be neglected through the analysis process for simplicity. However, they may significantly affect the dynamic behavior of the soil-foundation system. In this study, a series of 3D finite-element Direct-solution steady-state harmonic analyses were carried out using ABAQUS/CAE software to investigate the impacts of interlayers on the dynamic response of a cast in place pile group subjected to horizontal harmonic load. The experimental data of a 3×2 pile group testing was used to verify the numerical modeling. The effects of thickness, depth, and shear modulus of the interlayers on the dynamic response of the pile group are investigated. The simulations were conducted on both stiff and soft soils. It was found that the soft interlayers affect the frequency-amplitude curve of the system only in frequencies higher than 70% of the resonant frequency of the base soil. While, the effect of stiff interlayer in soft base soil started at frequency of 35% of the resonant frequency of the base soil. Also, it was observed that a shallow stiff interlayer increased the resonant amplitude by 11%, while a deep one only increased the resonant frequency by 7%. Moreover, a shallow soft interlayer increased the resonant frequency by 20% in soft base soils, whereas, it had an effect as low as 6% on resonant amplitude. Also, the results showed that deep soft interlayers increased the resonant amplitude by 17 to 20% in both soft and stiff base soils due to a reduction in lateral support of the piles. In the cases of deep thick, soft interlayers, the resonant frequency reduced significantly, i.e., 16 to 20%. It was found that the stiff interlayers were most effective on the amplitude and frequency of the pile group.

• Interaction and multiscale mechanics
• /
• v.1 no.4
• /
• pp.437-448
• /
• 2008

This paper examined the stability of high-dense dislocation substructures (HDDSs) associated with martensite laths in High Cr steels supposed to be used for FBR, based on a series of dislocation dynamics (DD) simulations. The DD simulations considered interactions of dislocations with impurity atoms and precipitates which substantially stabilize the structure. For simulating the dissociation processes, a point defect model is developed and implemented into a discrete DD code. Wall structure composed of high dense dislocations with and without small precipitates were artificially constructed in a simulation cell, and the stability/instability conditions of the walls were systematically investigated in the light of experimentally observed coarsening behavior of the precipitates, i.e., stress dependency of the coarsening rate and the effect of external stress. The effect of stress-dependent coarsening of the precipitates together with application of external stress on the subsequent behavior of initially stabilized dislocation structures was examined.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.5 no.1
• /
• pp.52-58
• /
• 2005

We have developed a Group Method of Data Handling (GMDH) type algorithm for designing multi-layered neural networks. The algorithm is general enough that it will accept any number of inputs and any sized training set. Each neuron of the resulting network is a function of two of the inputs to the layer. The equation for each of the neurons is a quadratic polynomial. Several forms of the equation are tested for each neuron to make sure that only the best equation of two inputs is kept. All possible combinations of two inputs to each layer are also tested. By carefully testing each resulting neuron, we have developed an algorithm to keep only the best neurons at each level. The algorithm's goal is to create as accurate a network as possible while minimizing the size of the network. Software was developed to train and simulate networks using our algorithm. Several applications were modeled using our software, and the result was that our algorithm succeeded in developing small, accurate, multi-layer networks.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.273-275
• /
• 1999

This paper presents a dynamic equivalencing method in large electric power system for stability analysis. This method of modeling simplified equivalents for parts of the network outside the study area is to evaluate the stability of a study area modeled in detail. Generators are closely coupled in an electrical sense tend to swing together in groups during disturbances, and this behavior can be exploited to reduce the size of the power system model. The characteristics of generators swing together are referred to as coherency Coherency groups whose generators state trajectory are similar to the other generators state trajectory in the same coherency group by a certain disturbance. In this paper, procedures for forming dynamic equivalents of control devices of coherency-based generating units are proposed and the aggregation of the control devices such as excitation system and governor-turbine system is accomplished by this method. This method can deal with the aggregation of the same type of control devices and combination of hydro and steam unit or the many types of excitation systems. etc. This method is shown to be efficient in reducing the number of control device of generating units with small error in the study group by result of case study presented latter part of this paper.

• Food Science of Animal Resources
• /
• v.29 no.1
• /
• pp.47-54
• /
• 2009

Predictive modeling was applied to study the growth of microorganisms related to spoilage in frankfurter sausage containing various levels of dietary fiber (0, 1, 2, and 3%) from rice bran and to estimate its shelf-life. Using the Baranyi model, total viable cells, anaerobic and psychrotrophic bacteria were measured during 35 days of cold storage ($<4{\pm}1^{\circ}C$). The lag times (LT) demonstrated by control and treatment groups were 6.28, 623, 6.24, and 6.25 days, respectively. The growth rate of total viable cells in each group were 0.95, 0.91, 0.92, and 0.91 (Log CFU/g/day), respectively. The anaerobic and psychrotrophic bacteria had lower initial ($y_0$) and maximal bacterial counts ($y_{max}$) than total viable cells. Also, the anaerobic and psychrotrophic bacteria possessed lower growth rate and longer lag time than total viable cells. The estimated shelf-life of frankfurter containing rice bran fiber by the growth rate of total viable cells was 7.8, 7.9, 7.9, and 7.7 days, respectively. There were no significant differences in shelf-life as a function of fiber content. In other words, the addition of dietary fiber in sausage did not show the critically hazardous results in growth of microorganism. The 12 predictive models were then characterized by high $R^2$, and small RMSE. Furthermore, $B_f$ and $A_f$ values showed a very close relationship between the predictive and observed data.

• Geomechanics and Engineering
• /
• v.10 no.5
• /
• pp.599-615
• /
• 2016

The present research presents experimental and finite element studies to investigate the behavior of piled raft-tunnel system in a sandy soil. In the experimental work, a small scale model was tested in a sand box with load applied vertically to the raft through a hydraulic jack. Five configurations of piles were tested in the laboratory. The effects of pile length (L), number of piles in the group and the clearance distance between pile tip and top of tunnel surface (H) on the load carrying capacity of the piled raft-tunnel system are investigated. The load sharing percent between piles and rafts are included in the load-settlement presentation. The experimental work on piled raft-tunnel system yielded that all piles in the group carry the same fraction of load. The load carrying capacity of the piled raft-tunnel model was increased with increasing (L) for variable (H) distances and decreased with increasing (H) for constant pile lengths. The total load carrying capacity of the piled raft-tunnel model decreases with decreasing number of piles in the group. The total load carrying capacity of the piles relative to the total applied load (piles share) increases with increasing (L) and the number of piles in the group. The increase in (L/H) ratio for variable (H) distance and number of piles leads to an increase in piles share. ANSYS finite element program is used to model and analyze the piled raft-tunnel system. A three dimensional analysis with elastoplastic soil model is carried out. The obtained results revealed that the finite element method and the experimental modeling are rationally agreed.

• Journal of Biosystems Engineering
• /
• v.35 no.2
• /
• pp.91-99
• /
• 2010

A Model of small scale total mixed rations(TMR) plant which can be utilized round bales was developed, tested and analyzed in this study. This study consist of two parts. One is development of a small scale TMR plant model which was already reported at the previous paper. This is the second part of the study. For the study, a series of tests of the model plant were performed and its costs was analyzed. Also, the break-even point of the model plant by comparing with market price of commercial TMR feed was determined. Results of the research are summarized as follows ; As the results of mixing test, the average coefficient of variation(CV) value for mixing of the feed was 13.0 % at the gate of the mixer. The production cost was estimated as 8,298 won/head for dairy cattle farm and 2,495 won/head for beef cattle farm, when producing 8 batch a day. Also, it is recommended to utilize the model plant when farm size is over 79 heads for dairy cattle farm and 113 heads for beef cattle farm. As an overall conclusion, the model plant designed for farm size TMR feed mill will be very useful model for both beef cattle and dairy farms in Korea. Also it is expected that the capital investment for the model plant can be recovered with 8 months compare with purchasing commercial TMR feed if the model plant feeds 1,000 beef cattle approximately.

• Korea Journal of Hospital Management
• /
• v.29 no.2
• /
• pp.57-79
• /
• 2024

Purpose: The present study identified the determinants in the development of intrapreneurial intention in small and medium-sized local hospitals. A careful literature review led to the development of a conceptual model which identified two types of employee competence-individual competence and managerial competence-to influence intrapreneurial orientation positively. It was hypothesized that intrapreneurial orientation predicts intrapreneurial intention and is mediated by intrapreneurial commitment. Methodology/Approach: The target population was chosen from two medical institutions of 'D' Hospital and 'E' Geriatric Hospital in Changwon City, South Korea. Samples were collected from 299 respondents who completed a structured questionnaire. Findings: The results from a structural equation modeling statistical analysis indicated that (1) individual competence and managerial competence positively and significantly predict intrapreneurial orientation, (2) intrapreneurial orientation positively and significantly influences intrapreneurial intention, (3) intrapreneurial commitment partially mediates the relation of intrapreneurial orientation to intrapreneurial intention, and (4) the mediation effect of intrapreneurial commitment was significant in the medical-personnel group, but not in the non-medical group. Practical Implications: Overall findings from the present work provide vital insights into understanding the preconditions for developing employee intrapreneurship in small and medium-sized local hospitals.

• Economic and Environmental Geology
• /
• v.54 no.1
• /
• pp.69-76
• /
• 2021

This study is to identify the mineralogical properties of caprock samples from drilling cores of the Pohang basin, which is the research area for the demonstration-scale CO2 storage project in Korea. The interaction of water-rock-gas that can occur due to CO2 injection was identified using geochemical modeling. Results of mineralogical studies, together with petrographic data of caprock and data on the physicochemical parameters of pore water were used for geochemical modeling. Modelling was carried out using the The Geochemist's Workbench 14.0.1 geochemical simulator. Two steps of modeling enabled prediction of immediate changes in the caprocks impacted by the first stage of CO2 injection and the assessment of long-term effects of sequestration. Results of minerlaogical analysis showed that the caprock samples are mainly composed of quartz, K-feldspar, plagioclase and a small amount of pyrite, calcite, kaolinite and montmollonite. After the injection of carbon dioxide, the porosity of the caprock increased due to the dissolution of calcite, and dawsonite and chalcedony were precipitated as a result of the dissolution of albite and k-feldspar. In the second step after the injection was completed, the precipitation of dawsonite and chalcedony occurred as a result of dissolution of calcite and albite, and the pH was increased due to this reaction. Results of these studies are expected to be used as data to quantitatively evaluate the efficiency of mineral trapping capture in long-term storage of carbon dioxide.