• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.473-480
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• 2014

Upon setting up a dedicated plastic greenhouse for tomato cultivation developed by the Rural Development Administration on the Gyehwa reclaimed land, this study was aimed at analyzing the problems can be occurred in the installation of plastic greenhouse on reclaimed lands as well as finding out solutions for improvement. A relatively cheaper wooden pile was used in the installation in order to supplement the soft ground conditions. Based on the results of ground investigation of the installation site, both the allowable bearing capacity and pulling resistance of the wooden pile with a diameter of 150 mm and a length of 10 m were computed and came out to be 30.645 kN. It was determined that the values were enough to withstand the maximum compressive force (17.206 kN) and the pullout force (20.435 kN) that are generally applied to the greenhouse footing. There are three problems aroused in the process of greenhouse installation, and the corresponding countermeasures are as follow. First, due to the slightly bent shape of the wooden pile, there were phenomenon such as deviation, torsion, and fracture when driving the pile. This could be prevented by the use of the backhoe (0.2) rotating tongs, which are holding the pile, to drive the pile while pushing to the direction of the driving and fixing it until 5 m below ground and applying a soft vibrating pressure until the first 2 m. Second, there exists a concrete independent footing between the column of the greenhouse and the wooden pile driven to the underground water level. Since it is difficult to accurately drive the pile on this independent footing, the problem of footing baseplate used to fix the column being off the independent footing was occurred. In order to handle with this matter, the diameter of the independent footing was changed from 200 mm to 300 mm. Last, after films were covered in the condition that the reinforcing frame and bracing are not installed, there was a phenomenon of columns being pushed away by the strong wind to the maximum of $11m{\cdot}s^{-1}$. It is encouraged to avoid constructions in winter, and the film covering jobs always to be done after the frame construction is completely over. The height of the independent footing was measured for 9 months after the completion of the greenhouse installation, and it was found to be within the margin of error meaning that there was no subsidence. The extent to the framework distortion and the value of inclinometers as well showed not much alteration. In other words, the wooden pile was designed to have a sufficient bearing capacity.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.1-11
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• 2015

In recent high performance computing system, GPGPU has been widely used to process general-purpose applications as well as graphics applications, since GPU can provide optimized computational resources for massive parallel processing. Unfortunately, GPGPU doesn't exploit computational resources on GPU in executing general-purpose applications fully, because the applications cannot be optimized to GPU architecture. Therefore, we provide GPU research guideline to improve the performance of computing systems using GPGPU. To accomplish this, we analyze the negative factors on GPU performance. In this paper, in order to clearly classify the cause of the negative factors on GPU performance, GPU core status are defined into 5 status: fully active status, partial active status, idle status, memory stall status and GPU core stall status. All status except fully active status cause performance degradation. We evaluate the ratio of each GPU core status depending on the characteristics of benchmarks to find specific reasons which degrade the performance of GPU. According to our simulation results, partial active status, idle status, memory stall status and GPU core stall status are induced by computational resource underutilization problem, low parallelism, high memory requests, and structural hazard, respectively.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.249-258
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• 2016

In this research, we analyzed the research and development process of small and medium enterprises, and diagnosed the problem of the research and development process of domestic small and medium enterprises, and evaluated the influence of innovative ability on the speed of research and development and corporate performance. In evaluating these effects, it is possible to grasp the direction of power generation according to the type of analysis, taking into account the meltdown factor of factors related to innovative capabilities. The main purpose of this research is to confirm the influence on the speed of research and development according to the innovative capacity and business environment and to verify the reliability and validity of the research by Klumbach alpha Was used. In this research, we analyzed how the speed of R & D affects R & D activities, it is a research aimed at the necessity of a resource-based approach to the internal capacity of a company, Have a valuable value. Based on the influence on the company, each factor is a research that analyzed the influence on R & D and financial indicators through maintaining company's development level, Research that has practical value that can base on the development of R & D capacity on corporate strategy formulation.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Journal of the Korean School Mathematics Society
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• v.20 no.4
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• pp.521-536
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• 2017

One of difficulties with which teachers meet is to have underachievers with no willingness and motivation for study involved in class. Mathematics underachiever are average or above average in their intelligence but their actual achievement in mathematics did not coincide to their intellectual capabilities. The teaching strategy for them is to motivate them to try to study mathematics and to experience the improvement in their mathematics grade. In this paper, we choose flipped classroom as the strategy of teaching basic mathematics to math underachievers and applied it to them. Then we wanted to make sure the possibility for applying flipped classroom to teaching math underachievers through the analysis of change in the scholastic achievement of students in mathematics and mathematical disposition. The results of this study are as followings; First, when we taught basic math to underachievers using a flipped classroom, we confirm that math underachievers with active participation improved scholastic achievements significantly. Second, the flipped classroom was led to positive effects in an affective domain. In particular, it showed the most noticeable change in the area of willingness to math problem-solving and perception about the value of mathematics.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.2
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• pp.135-139
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• 2018

This study was conducted to evaluate the forage production and feed value of Sasa borealis (S. borealis) in Jeju Island in order to improve the utilization of Sasa borealis and to help mitigate the problem of reduced plant species diversity caused by S. borealis in Hanlla Mountain. To investigate the forage production, three quadrat structures were installed in the S. borealis natural community in the middle part of Hanlla Mountain. From May to October 2017, S. borealis in quadrats was cut at a fixed time of each month, and then forage production and regenerated acidity per kg/ha were evaluated. For the evaluation of feed value, compositional analysis was performed on the monthly samples. In vitro digestion experiments were carried out using cannula mounted Hanwoo. In vitro neutral detergent fiber digestibility(IVNDFD) and in vitro acid detergent fiber digestibility(IVADFD) were measured after the experiment. Forage production of S. borealis showed relatively good regeneration ability in May and June, but the regeneration ability decreased as the cutting was repeated. In order to use S. borealis as a forage, it is considered efficient to feed black goats with good fiber decomposition or horses good palatability to S. borealis and relatively good digestibility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2291-2297
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• 2015

This paper presents a vehicle detection system using the video as a input image what has moving of vehicles.. Input image has constraints. it has to get fixed view and downward view obliquely from top of the road. Road detection is required to use only the road area in the input image. In introduction, we suggest the experiment result and the critical point of motion history image extraction method, SIFT(Scale_Invariant Feature Transform) algorithm and histogram analysis to detect vehicles. To solve these problem, we propose using applied Gaussian Mixture Model(GMM) that is the Vehicle Detection GMM(VDGMM). In addition, we optimize VDGMM to detect vehicles more and named VDGMM 2.0. In result of experiment, each precision, recall and F1 rate is 9%, 53%, 15% for GMM without road detection and 85%, 77%, 80% for VDGMM2.0 with road detection.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.306-313
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• 2005

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. But most of statistical inferences are not definite because of sample size, measurement number, measuring , instruments, etc. And there have been few studies about the marginal fit of Computer-aided Cercon crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made using computer-aided milled Cercon crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and methods. The in vitro marginal discrepancies of computer-aided milled Cercon crowns and control groups (metal ceramic crowns) were evaluated and compared. The crowns were made from one extracted maxillary central incisor prepared by milling machine. 30 crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Results. The means and standard deviations of the marginal fit were 85$\pm$22$\mu$m for the control group and 91$\pm$15$\mu$m for the Cercon crowns. The t-test of the marginal discrepancies between Cercon crowns and metal-ceramic crowns were performed. Significant differences were not found between groups (P=0.230>.05). Based on the criterion of 120$\mu$m as the limit of clinical acceptability, the mean marginal fits of Cercon crowns and metal-ceramic crowns were acceptable. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were 85$\pm$22$\mu$m for the control (metal-ceramic crowns), 91$\pm$15$\mu$m for Cercon crowns. 2. The Cercon crowns showed slightly larger marginal gap discrepancy than the control but marginal gap between Computer-aided milled Cercon crowns and metal ceramic crowns did not showed significant difference (P>.05). 3. The Cercon crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.363-378
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• 2005

Statement of problem. Hydroxyapatite(HA) coated titanium surfaces have not yet showed the reliable osseointegration in various conditions. Purpose. This study was aimed to investigate microstructures, chemical composition, and surface roughness of the surface coated by the hydrothermal method and to evaluate the effect of hydrothermal coating on the cell attachment, as well as cell proliferation. Material and Methods. Commercially pure(c.p.) titanium discs were used as substrates. The HA coating on c.p. titanium discs by hydrothermal method was performed in 0.12M HCl solution mixed with HA(group I) and 0.1M NaOH solution mixed with HA(group II). GroupⅠ was heated at 180 $^{\circ}C$ for 24, 48, and 72 hours. GroupⅡ was heated at 180 $^{\circ}C$ for 12, 24, and 36 hours. And the treated surfaces were evaluated by Scanning electron microscopy(SEM), Energy dispersive X-ray spectroscopy(EDS), X-ray photoelectron spectroscopy(XPS), X-ray diffraction method(XRD), Confocal laser scanning microscopy(CLSM). And SEM of fibroblast and 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay were used for cellular responses of the treated surfaces. Results. The color of surface changed in both groups after the hydrothermal process. SEM images showed that coating pattern was homogeneous in group II, while inhomogeneous in group I. H72 had rosette-like precipitates. The crystalline structure grew gradually in group II, according to extending treatment period. The long needle-like crystals were prominent in N36. Calcium(Ca) and phosphorus(P) were not detected in H24 and H48 in EDS. In all specimens of group II and H72, Ca was found. Ca and P were identified in all treated groups through the analysis of XPS, but they were amorphous. Surface roughness did not increase in both groups after hydrothermal treatment. The values of surface roughness were not significantly different between groups I and II. According to the SEM images of fibroblasts, cell attachments were oriented and spread well in both treated groups, while they were not in the control group. However, no substantial amount of difference was found between groups I and II. Conclusions. In this study during the hydrothermal process procedure, coating characteristics, including the HA precipitates, crystal growth, and crystalline phases, were more satisfactory in NaOH treated group than in HCl treated group. Still, the biological responses of the modified surface by this method were not fully understood for the two tested groups did not differ significantly. Therefore, more continuous research on the relationship between the surface features and cellular responses seems to be in need.

• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.67-79
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• 2010

Korea water resources corporation (K-Water) has developed the real-time water resources management system for the Nakdong and the Geum River basin to efficiently operate multi-purpose dams in the basins. This study has extended to the Han River basin for providing an effective ending target storage of a month to the real-time water resources management system using Sampling Stochastic Dynamic Programming (SSDP), consequently increasing the efficiency of the reservoir system. The optimization model were developed for three reservoirs, named Soyang, Chungju, and Hwacheon, with high priority in terms of the amounts of effective capacity and water supply for the basin. The number of storage state variable for each dam to set an optimization problem has been assigned from the results of sensitivity analysis. Compared with the K-water operating policy with the target water supply elevations, the optimization model suggested in this study showed that the shortfalls are decreased by 37.22 MCM/year for the required water demands in the basin, even increasing 171 GWh in hydro electronic power generation. In addition, the result of a reservoir operating system during the drawdown period applied to real situation demonstrates that additional releases for water quality or hydro electronic power generation would be possible during the drawdown period between 2007 and 2008. On the basis of these simulation results, the applicability of the SSDP model and the reservoir operating system is proved. Therefore, the more efficient reservoir operation can be achieved if the reservoir operating system is extended further to other Korean basins.