• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.34-34
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• 1993

The gelation phenomena of N-methylolated PAAm (M-PAAm) in aqueous media was studied. The critical gelation concentration (CGC) was very close to the calculated $C^*$ of the scaling theory. But the CGC of lower MW M-PAAm deviated from $C^*$ due to contamination of small molecules. We propose that the CGC is the close packing configuration of polymer molecules in solution. The experimental results of the gelation of M-PAAm/PAAm mixture proved that the close packing configuration is essential to make a gel. We calculated the minimum quantity of M-PAAm to make M-PAAm/PAAm mixture a gel by using the close packing configuration. We used a lattice model.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2148-2154
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• 2013

Three push-pull organic semiconductors, TPA-$Th_3$-MMN (1), TPA-ThTT-MMN (2), and TPA-ThDTT-MMN (3), comprising a triphenylamine donor and a methylene malononitrile acceptor linked by various ${\pi}$-conjugated thiophene units were synthesized, and the effects of the ${\pi}$-conjugated bridging unit on the photovoltaic characteristics of solution-processed small-molecule organic solar cells based on these semiconductors were investigated. Planar bridging units with extended ${\pi}$-conjugation effectively facilitated intermolecular ${\pi}-{\pi}$ packing interactions in the solid state, resulting in enhanced $J_{sc}$ values of the SMOSCs fabricated with bulk heterojunction films.

• Journal of Ocean Engineering and Technology
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• v.2 no.2
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• pp.130-137
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• 1988

This thesis introduced that character of a treatment technique for a mading synthetic resin Hifiow-Ring. The material system of packings make an experiment air$NH_{3}$/air$H_{2}SO_{4}$, $SO_{2}$-air/NaOH, $NH_{3}$-air/$/H_{2}SO_{4}$ under general conditions. Lattices packing compared with conventional packings was proved low pressure loss and high separation efficiency for high loading per trans unit. And an inflow materal tested for absorption and rectification, it made an experiment under a range regular temperature, low energy and small amount of money. That made possible in simple equation, volume material tranfer coefficient$\beta_{L}$ . a by absorption or $\beta_{V}$ .a calculated in all range loading. The peculiarity pressure loss $\Delta\;P/NUT_{ov}$ for Hiflow-ring contributed to a fall cost of energy, a grade number of a vacuum rectification and absorption calculation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.59-65
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• 2019

In many industries, particle packing is adopted quite frequently. In the particle packing process, the Discrete Element Method (DEM) can analyze the multi-collision of particles efficiently. Two types of contact models are frequently used for the DEM. One is the linear spring model, which has the fastest calculation time, and the other is the Hertz-Mindlin model, which is the most frequently used contact model employing the DEM. Meanwhile, very tiny particles in the micrometer order are used in modern industries. In the micro length order, surface force is important to decreased particle size. To consider the effect of surface force in this study, we performed a simulation with the Hertz-Mindlin model and added the Johnson-Kendall-Roberts (JKR) theory depicting surface force with surface energy. In addition, three contact models were compared with several parameters. As a result, it was found that the JKR model has larger residual stress than the general contact models because of the pull-off force. We also validated that surface force can influence particle behavior if the particles are small.

• Korean Journal of Agricultural Science
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• v.39 no.1
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• pp.151-159
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• 2012

This paper analyzes the consumers' preference for packaged apple and derives the measures to vitalize the distribution of packaged apple. To do this, survey was conducted for consumers in large cities, Seoul, Busan, and Daegu to observe their purchasing behavior and satisfaction both for packaged and unpackaged apple. Survey was focused to how they are satisfied with several attributes of package such as size, appearance, content, material, and label. On the basis of the survey results, the values of the package attributes were estimated. Survey results show that consumers tend to buy unpackaged apple rather than packaged apple. About 34 percent out of 313 respondents have ever purchased apple packed with paper box while only 10.5 percent have an experience to buy packaged apple with transparent box. Most respondents answered they preferred the package of five to six apples and 1.3 kilograms most. They preferred mid or large size apple. Estimation of the values of the package attributes using the conjoint analysis shows that consumers are giving the highest value to the price of packing material. It means that consumers are reluctant to the extra payment resulted from packing the apple. Therefore, the efforts to reduce the cost of packing apple should be made steadily. In order to vitalize the distribution of small packaged apple, the package should contain high quality apple with high sugar content, proper size, good appearance, and so on. And it needs to be promoted to the consumers that small packaged apple are not inferior to apple packed with paper box.

• Journal of Digital Contents Society
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• v.15 no.3
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• pp.373-380
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• 2014

Malicious codes uses generic unpacking technique to make it hard for analyzers to detect their programs. Recently their has been several researches about generic packet to prevent or detect these techniques. And they try to focus on the codes that repeats while generic packing is doing compression because generic packing technique executes after it is decompressed. And they try to focus on the codes that repeats while generic packing is doing compression because generic packing technique executes after it is decompressed. Therefore, this makes a interesting performance which shows a similar address value from the codes which are repeated several times what is different from the normal program codes. By dividing these codes into regularly separated areas we can find that the generic unpacking codes have a small entropy value compared to normal codes. Using this method, it is possible to identify any program if it is a generic unpacking code or not even though we do not know what kind of algorithm it uses. This paper suggests a way of disarming the generic codes by using the low value entropy value which comes out from the Opcode addresses when generic unpacking codes try to decompress.

• Korean Journal of Agricultural Science
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• v.31 no.2
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• pp.149-160
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• 2004

This study had carried out an analysis of leaf tobacco production cost by cost items, growing stages, and farm sizes per 10a to provide the basic data for determination of the purchasing price of leaf tobacco by KT&G. Considering the survey results of 12 tobacco farm households, the composition rates of production cost by items revealed as 7-10% for land service, 5-22% for depreciation, 13-25% for material costs, 50-65% for labour cost respectively. The production cost of leaf tobacco by growing stages were shown as 15.3% in nursery bed period, 32.3% in main growing period in field, 30.8% in harvesting period and 21.6% in packing period. The magnitude of wage expenditure was appeared as harvesting stage, packing stage, growing stage on main field and nursery bed stage in order. The amount of material costs were revealed as the growing stage in main field, harvesting stage, nursery bed stage and packing stage respectively. The production costs of leaf tobacco per 10a by farm sizes were shown as 1,615,879won for small farm, 1,446,896won for medium farm and 1,454,408won for large farm respectively. The production cost of leaf tobacco had shown decreasing tendency according to increasing farm sizes. To promote the international market competitiveness of leaf tobacco producing farms, labour saving production technologies and cost effective farm size to decrease tobacco production cost should be developed.

• Journal of the Korean Ceramic Society
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• v.45 no.8
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• pp.439-442
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• 2008

A series of reaction-sintered SiC was fabricated from preforms with varying volume fractions of two resin-coated SiC particles of different sizes (63 and $18{\mu}m$). The electrical resistivity and mechanical strength were eventually optimized at the small particle volume fraction of $0.3{\sim}0.4$, at which point the porosity of the preform was minimized. This study experimentally proves that additional processes after the formation of the preform, such as silicon infiltration and reaction sintering, do not apparently alter the optimum volume fraction of the preform packing, predicted by an existing analytical model based on solid packing. Thus, the volume fraction of particles of different sizes can be determined practically through the solid packing model to fabricate RSSCs with optimal properties.

• Design & Manufacturing
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• v.14 no.4
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• pp.25-39
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• 2020

In this study, an edge device that monitors the injection molding process by measuring the mold vibration(acceleration) signal and the mold surface temperature was developed and evaluated its performance. During injection molding, signals of the injection start, V/P switchover, and packing end sections were obtained through the measurement of the mold vibration and the injection time and packing time were calculated by using the difference between the times of the sections. Then, the mold closed and mold open signals were obtained using a magnetic hall sensor, and cycle time was calculated by using the time difference between the mold closed time each process. As a result of evaluating the performance by comparing the process data monitored by the edge device with the shot data recorded on the injection molding machine, the cycle time, injection time, and packing time showed very small error of 0.70±0.38%, 1.40±1.17%, and 0.69±0.82%, respectively, and the values close to the actual were monitored and the accuracy and reliability of the edge device were confirmed. In addition, it was confirmed that the mold surface temperature measured by the edge device was similar to the actual mold surface temperature.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.127-130
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• 2005

The early stage of the self assembly for octadecyltrichlorosilane (OTS)-based monolayers is investigated using atomic force microscopy (AFM). Height measurements using AFM prove that the island height of the monolayers gradually increases with increasing the island size, and is close to the limiting value (h = $\sim$25 $\AA$) after d = $\sim$600 nm in size. Since the theoretical length of a covalently bound OTS molecule is 26.2 Å, the limiting value of the island height means that the islands with d ${\geq}$ 600 nm consist of close-packed, fully extended chains. The heights for the islands with d < 600 nm are lower than the limiting value and decrease with decreasing the island sizes. This observation indicates that the OTS molecules in the small islands are less densely packed, and that the packing densities of the islands increase as the islands grow in size.