• Journal of the Korean Wood Science and Technology
• /
• v.48 no.2
• /
• pp.196-205
• /
• 2020

The purpose of this study was to investigate a method for improving the physical and mechanical properties of laminated board made from oil palm trunk (OPT). The effects of pretreating the lamina with heat-pressure and altering the lamina composition of the laminated board were investigated. The outer third of OPT in cross-section had high-density wood, while the underlying third had low to medium density. The hot press was applied to pretreat the lamina that had low to medium density. The lamina were 1.5 cm in thickness, 5 cm in width, and 65 cm in length. The hot press was applied at 2.94 MPa or 4.41 MPa at 150 ℃ for 60 minutes, and the target thickness of the lamina was 1 cm. The three layers of the laminated board samples were bonded with isocyanate adhesive at a glue spread of 300 g/㎡ and cold pressed at 0.98 MPa for 3 h. The laminated board samples were tested according to Japanese Agricultural Standard (JAS) 234-2003. The results showed that the densification of the inner lamina did not significantly affect the physical-mechanical properties of the laminated board produced. However, the laminated board made with high-density laminas for the outer layers fulfilled the JAS 234-2003 standard for the modulus of elasticity and the modulus of rupture.

• The Korean Journal of Pesticide Science
• /
• v.6 no.1
• /
• pp.25-30
• /
• 2002

Quantitative structure-toxicity relationships (QSTRs) between various physicochemical parameters of substituents in new herbicidal N-phenyl-3,4-dimethylphthalimide derivatives and their discriminate score (DS) for chronic and acute toxicities against mouse and rat evaluated using TOPKAT calculation were discussed quantitatively. From the basis on the findings, it was shown that carcinogenicities of female was higher than that of male and mouse had higher tendency than rat. The STR analyses results of Hansch-Fujita type equations suggested that mouse (female & male) and rat male except rat female are dependent on LUMO energy commonly in carcinogenicity. The selective carcinogenicity factor of two species between male mouse and female mouse is dependent on optimal value (ca. $(L)_{opt.}=5.0{\AA}$) for length of $R_2$-substituent mainly. According to Free-Wilson approach, in the case of rat male, alkyl and aryl substituents were superior and in the other case, contribution of fluoro group substituents were superior to chronic toxicity.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.6
• /
• pp.57-63
• /
• 2000

A multi-branch thermo-optic switch has a problem that driving powers in the switching states are different from each other; the power consumption for the inner output port is more than twice as large as that form the outer output port. In this pater, to solve this problem unequal width heaters and the waveguide structure with a thin overcladding layer are proposed in a four-branch thermo-optic switch. The proposed structure is fabricated with the polymer materials with high index difference, Teflon and polyimides. The fabricated device was measured at the wavelength of 1550 nm. The measured characteristics exhibit the smaller difference in the power consumption between the switching states and the driving power les than the previous four-branch thermo-optic switch with equal width heaters. As for the device performance, the crosstalk is better than - 16 dB at about 310 ~ 390 mW, the insertion loss is 4.7 dB, and the switching time is less than 1 ms.

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.265-275
• /
• 2019

The purpose of this study was to explore factors that physical education graduate students in graduate school of education drop out of teacher appointment examination of secondary school by using Ecological Model. The in-depth interview was conducted for 10 physical education graduate students studying in school of education. As an aspect of the intrapersonal component, the effort to apply how participants'current job positively affects their preparation for teacher appointment examination is required and they need to clearly decide academic priorities to prepare for teacher appointment examination. As an aspect of interpersonal component, participants are negatively affected by subjective norm, thereby providing personalized mentoring program is required. As an aspect of organizational component, limited tuition support and inappropriate place to study are emphasized, so practical helps like sports practice instructor or teacher appointment examination preparation class is required. Finally, this study suggests the introduction of integrated system for teacher appointment examination.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.44 no.4
• /
• pp.32-42
• /
• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.12
• /
• pp.277-284
• /
• 2022

In this paper, we proposes a method of optimizing the processing order of skids to minimize the span time in a conveyor environment of the shipbuilding subassembly process. The subassembly process consists of a series of fixed tasks where the required work time is varied according to the skid type. The loading order of skids on a conveyor which determines the span time should be properly optimized and the problem size exponentially increases with the number of skids. In this regard, we propose a novel method called UniDev by defining a measure of the mean-absolute-deviation about the time difference among simultaneously processed tasks and iteratively improving it. Through simulations with various numbers of skids and processes, it was observed that our proposed method can efficiently reduce the overall work time compared with the multi-start and the 2-OPT methods.

• Reproductive and Developmental Biology
• /
• v.31 no.1
• /
• pp.15-20
• /
• 2007

To search of a new porcine pheromonal odorant for biostimulation control system technologies to offer a potentially useful and practical way to improve reproductive efficiency in livestock species, the two dimensional quantitative structure-activity relationship (QSAR) models between physicochemical parameters as descriptors of 2-cyclohexyloxytetrahydrofurane (A), 2-phenoxytetrahydrofurane (B) analogues and binding affinity constant ($p[Od.]_{50}$) for porcine odorant-binding protein (pOBP) as receptor of pig pheromones were derived and disscused. The statistical quality of the optimized 2D-QSAR model is good ($r^{2}=0.964$) and accounts for 96.4% of the variance in the binding affinity constants. It was found that the binding affinity constants were dependent upon the optimal value, $(SL)_{opt.}=1.418$ of substituent lipole (SL) in molecules. Therefore, the SL constant was very important factor for binding affinity.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.5
• /
• pp.366-372
• /
• 2015

Ocean energy is one of the most promising renewable energy resources. In particular, South Korea is one of the countries where it is economically and technically feasible to develop tidal current power plants to use tidal current energy. In this study, based on the design code for HARP_Opt (Horizontal axis rotor performance optimizer) developed by NREL (National Renewable Energy Laboratory) in the United States, and applying the BEMT (Blade element momentum theory) and GA (Genetic algorithm), the optimal shape design and performance evaluation of the horizontal axis rotor for a 200-kW-class tidal current turbine were performed using different numbers of blades (two or three) and a pitch control method (variable pitch or fixed pitch). As a result, the VSFP (Variable Speed Fixed Pitch) turbine with three blades showed the best performance. However, the performances of four different cases did not show significant differences. Hence, it is necessary when selecting the final design to consider the structural integrity related to the fatigue, along with the economic feasibility of manufacturing the blades.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.996-1003
• /
• 2021

The purpose of this study is to evaluate the reliability of repeated measurements of several dental scanners. Blue-lighted scanners, white-light scanners and optical-type scanners are used in the study of repeatability in this study. The measurement results were calculated as root mean square (RMS) and the significance level was confirmed by applying the 1-way ANOVA statistical technique (𝛼=.05). According to the statistical analysis, the scanner with the largest RMS value was Z-opt group (38.2 ㎛. Next, D-white was 35.2 ㎛ and the group with the lowest RMS value was I-blue (34.1 ㎛). The comparison of RMS means between each group was not significant (p>.05). From this result, the blue light had the lowest error in repeatability of dental scanners, but no statistical significance. The conclusion of this study is that the study results are clinically acceptable.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.3
• /
• pp.95-103
• /
• 2021

I began to produce a series of works based upon the plastic element as a visual transmission -such as points, lines, sides, volumes and cubics, movements with in time, and space- which appeared in the optical art, that emerged in the 1950s and the early 1960. My works, which portray the natural scenes such as mountains, trees, and flowers that are commonly seen around us, are completed by drawing, erasing, filling with many points and overlapping. My works also ignore the scenography. All artistic activities must be based upon humanistic values and ultimately need to work for human being. The work with application of opt art did not use the perspective, but diverse colors. The work with application of opt art did not use the perspective, but diverse colors. The work tried to express more diverse impression rather than the emotion from the familiar perspective. We hope, therefore, my works give pleasure and satisfaction to these who come to see them.