• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.2
• /
• pp.265-276
• /
• 2000

Crop-animal systems which form the backbone of agriculture in the tropics are discussed with reference to their characteristics, economic importance of animals, genesis and types of crop-animal systems, relevance and potential importance, and priorities for research and development. These production systems are found across all agroecological zones: rain-fed temperate and highland systems, semi-arid and arid tropics, and sub-humid and humid tropics: the last four are priority areas in Asia. The potential importance of these systems in Asia is reflected in their advantages, synergism and complimentarity, economic benefits and contribution to sustainability. Illustrative case studies are cited which are appropriate to the two broad types of mixed farming systems: systems combining animals and annual cropping, and systems combining animals with perennial cropping with reference to Indonesia, Philippines, Malaysia, Sri Lanka, China and Nigeria. Priorities for research and development should address more complete use of the animal genetic resources, intensive utilisation of the feed resources, development-oriented utilisation of research results, minimizing animal diseases, and implementation of appropriate institutional and policy issues.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.5
• /
• pp.481-489
• /
• 2010

Experiments on laminar mixed convection in a vertical pipe were performed for the Re range 1,000-3,000, the $Gr_H$ range $10^5-10^8$, the Pr range 2,000-7,000, and aspect ratio range 1-7. Using the analogy concept, heat transfer systems were simulated by mass transfer systems. A cupric acid.copper sulfate electroplating system was adopted as the mass transfer system, and the mass transfer rates were measured. The measured Nu values were far greater than those previously reported because of the large value of pr in this experiment. As the aspect ratio in this study was not sufficiently large for the flow to be fully developed, the test results were similar to those for mixed convection on a vertical plate rather than that inside a long vertical pipe. It was concluded that the behavior of laminar mixed convection of a developing flow in a vertical pipe at a low aspect ratio and low $Gr_H$ is similar to that of laminar mixed convection in the vertical plate. As the aspect ratio and $Gr_H$ increase, the laminar mixed convection phenomena becomes similar to that observed in a fully developed flow in the vertical pipe.

• Polymer(Korea)
• /
• v.36 no.1
• /
• pp.53-58
• /
• 2012

The differences between single and mixed aluminium catalyst systems in the bulk polymerization of L-lactide were studied. $Al(O-i-Pr)_3$, TMA, TOA and TIBA were employed for the mixed-catalyst systems, and TIBA was chosen as a reference catalyst. For the $Al(O-i-Pr)_3$/TIBA catalyst system, the conversion of polymerization increased as the composition of $Al(O-i-Pr)_3$ in the mixed catalyst increased. The molecular weight of the resulting PLA reached to about 13000 g/mol, and the polydispersity index of the polymer from the $Al(O-i-Pr)_3$/TIBA catalyst was slightly increased than that of single catalyst. The higher molecular weight tail or shoulder was revealed in the GPC curve. The conversion of the TOA/TIBA catalyst system decreased as the composition of TOA in the mixed catalyst increased. The molecular weight of PLA prepared with TOA/TIBA catalysts increased up to 14000 g/mol. The Al compounds-mixed catalysts could produce a higher molecular weight tail or shoulder in the GPC curve, which may result in enhancement of mechanical properties of PLA.

• Journal of Korea Society of Industrial Information Systems
• /
• v.18 no.5
• /
• pp.51-58
• /
• 2013

A clock duty-cycle corrector (DCC) which is an essential device of clocking circuits for high-speed system-on-chip (SoC) design is introduced in this paper. The architectures and operation of conventional analog feedback DCCs and digital feedback DCCs are compared and analyzed. A new mixed-mode feedback DCC that combines the advantages of analog DCCs and digital DCCs to achieve a wider duty-cycle correction range, higher operating frequency, and higher duty-cycle correction accuracy is presented. Especially, the architectures and design of a mixed-mode duty-cycle amplifier (DCA) which is a core unit circuit of a mixed-mode DCC is presented in detail. Two mixed-mode DCCs based on a single-stage DCA and a two-stage DCA were designed in a 0.18-${\mu}m$ CMOS process, and it is proven that the two-stage DCA-based DCC has a wider duty-cycler correction range and smaller duty-cycle correction error.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.4
• /
• pp.667-674
• /
• 2007

Phase behavior for the mixed aqueous surfactant systems of cationic octadecyl trimethyl ammonium chloride (OTAC)/anionic ammonium dodecyl sulfate (ADS)/water was examined. Below the total surfactant concentrations of 1.5 m molal, mixed micelles were formed. At the total surfactant concentrations higher than 1.5 m molal, there appeared a region where mixed micelles and vesicles coexist. As the surfactant concentration increased, the systems looked very turbid and much more vesicles were observed. The vesicles were spontaneously formed in this system and their existence was observed by negative-staining transmission electron microscopy (TEM), small-angle neutron scattering (SANS) and encapsulation efficiency of dye. The vesicle region was where the molar fraction α of ADS to the total mixed surfactant was from 0.1 to 0.7 and the total surfactant concentration was above 5 × 10-4 molality. The size and structure of the vesicles were determined from the TEM microphotographs and the SANS data. Their diameter ranged from 450 nm to 120μm and decreased with increasing total surfactant concentration. The lamellar thickness also decreased from 15 nm to 5 nm with increasing surfactant concentration and this may be responsible for the decrease in vesicle size with the surfactant concentration. The stability of vesicles was examined by UV spectroscopy and zeta potentiometry. The vesicles displayed long-term stability, as UV absorbance spectra remained unchanged over two months. The zeta potentials of the vesicles were large in magnitude (40-70 mV) and the observed longterm stability of the vesicles may be attributed to such high ζ potentials.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.44 no.1
• /
• pp.26-36
• /
• 2021

The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation's characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles' route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.6
• /
• pp.77-91
• /
• 2023

Recently, there has been a worldwide increase in research and development on automated vehicles for commercialization. It is expected that the use of level 3 autonomous vehicles on continuous-flow roads will be introduced and will increase. Consequently, various studies have been conducted to investigate the impact of mixed traffic flow with automated vehicles based on the market penetration rate (MPR). However, these studies have been conducted independently, and the results have shown different trends. Therefore, this study attempted a quantitative analysis of the impact of automated vehicles on mixed traffic flow on uninterrupted roads through a meta-analysis. The results showed that the effect size estimated from an MPR of 75% or higher was statistically significant.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.1
• /
• pp.42-60
• /
• 2024

This study analyzed the characteristics of mixed traffic flows with autonomous vehicles on highway weaving sections and assessed the safety of vehicle-following pairs based on surrogate safety indicators. The intelligent driver model (IDM) was utilized to emulate the driving behavior of autonomous vehicles, and the weaving sections were divided into lengths of 300 and 600 meters for analysis within a micro-traffic simulation (VISSIM). Although significant differences were found in the average speed, density, and headway between the two sections through t-test results, no significant differences were observed when comparing the number of conflicts per indicator and the vehicle-following pair. Four safety indicators were selected for the mixed traffic evaluation based on their ability to represent risk levels similar to those perceived by drivers. The safety analysis, based on the selected four indicators, determined that autonomous vehicles following other autonomous vehicles were the safest pairing. Future research should focus on integrating these indicators into a single comprehensive index for analysis.

• Journal of the Korean Applied Science and Technology
• /
• v.22 no.3
• /
• pp.219-227
• /
• 2005

Competitive solvent extraction of the mixure of alkali metal and alkaline earth cation from water into organic solvent containing the crown ether carboxylic acid and anlogous crown ether phosphonic acid was investigated as follows. The lipophilic group is found to strongly influence to the selective extraction in the mixed systems from only alkali metal cation for sym-(n-decyldibenzo)-16-crown-5-oxyacetic acid $\underline{1}$ to mostly alkaline earth metal cation for sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid $\underline{3}$. Monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{2}$. and monoethyl-sym- bis]4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $\underline{4}$ showed good selectivity for $Na^+$ over $Mg^{2+}$, the second extracted ion. Structural variation in the crown ether phosphonic acid somewhat was influenced to the extraction selectivity in the mixed systems. when variation of the ionized group is influenced in the mixed systems, the selectivity of $Na^+$ as the second extracted ion was much better crown ether carboxylic acid $\underline{1}$ than crown ether phosphonic acid $\underline{2}$, while the efficiency of $Na^+$ extraction was better $\underline{2}$ (83% total loading) than $\underline{1}$ (32%).

• Applied Chemistry for Engineering
• /
• v.7 no.1
• /
• pp.101-108
• /
• 1996

The dynamic surface tension of GL12 (easily biodegradable nonionic surfactant and mild to skin), LAS and SLES aqueous solutions and that of mixed surfactant systems were measured by the maximum bubble pressure method at different mixing ratios. The effects of various salt such as NaCl, CsCl and urea on the dynamic surface tension of mixed surfactant systems were also studied. The dynamic surface tension of GL12 was not influenced by the presence of salts. On the contrary, the dynamic surface tensions of anionic surfactants (LAS and SLES) were significantly affected by the salts. In the mixed surfactant systems, the effect of salt increased as the composition of anionic LAS or SLES increased in the GL12/LAS and GL12/SLES mixtures.