• Asian-Australasian Journal of Animal Sciences
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• v.21 no.6
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• pp.769-775
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• 2008

This study was on the relative net income (RNI) for 18,286 Iranian Holstein cows from 799 herds, with first freshening between 1991 and 2000. Two kinds of production system, which differed mainly in milk pricing system and feed cost, were considered. Four different models adopted from the literature were examined to find the optimum model. They differed by the cost of rearing and growth after first calving and they needed different amounts of economic data at the farm level. Results showed that four measures of RNI were highly correlated (>0.96) and could be used equally to measure lifetime profitability of cows. Therefore, in herds without a regular system for recording economic and management data, use of the simplest model is recommended. Multiple regression analysis revealed that RNI was affected by age at first freshening, milk yield and days of productive life (DPL), regardless of production system, and a similar breeding goal could be defined for the two systems. Multiple regression analysis of RNI showed that in order to obtain an unbiased estimate of economic value for DPL, the per day milk yield, not total lifetime milk yield, should be included in the regression model along with DPL. Regression analysis suggested that it is possible to predict RNI using information on age at first freshening along with the length of first lactation and per day milk yield with a coefficient of determination ranging from 0.44 to 0.47.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.107-114
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• 2000

This work is aimed to develop a new type of the Push-Pull ultrasonic transducer that can provide higher sound pressure level and simpler internal structure than conventional types. The driving part of the newly designed transducer is positioned in the middle of the cylinder, and its optimum geometry is determined by using the FEM package, ANSYS. Through FEM model analysis, the effects of all of its geometrical variables such as transducer length, transducer radius, and the edge shape of the end cap have been examined, and the results have led to the optimum geometry. The newly designed transducer has been found to give better performance than that of traditional ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.1001-1010
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• 2001

In TLM method, Discrete Green's function ABC have been used when improved the exactness of analyzing in wide frequency band. But this technology has a complicated process to apply absorbing boundary, which means it needs additional numerical analyzing process to obtain discrete Green's function data. so, In this paper, we propose new Green's absorbing layer for simple process to apply absorbing boundary. newly proposed Green's absorbing layer is produced by applying of loss operation, loading discrete Green's function with attenuation. A state of optimum absorbing would be obtained by relation between increasing rate of loss, attenuation constant and length of green's absorbing layer. and then Analysts of waveguide BPF is carried out using Green's absorbing layer within state of optimum absorbing, then this result is in corrective agreement with the result applying traditional discrete Green's function ABC.

• Journal of Navigation and Port Research
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• v.36 no.9
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• pp.729-735
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• 2012

The primary wave energy conversion by a three-dimensional bottom-mounted oscillating water column (OWC) wave power device in regular waves has been studied. The linear potential boundary value problem has been solved following the boundary matching method. The optimum shape parameters such as the chamber length and the depth of the front skirt of the OWC chamber obtained through two-dimensional numerical tests in the frequency domain have been applied in the design of the present OWC chamber. Time-mean wave power converted by the OWC device and the time-mean second-order wave forces on the OWC chamber structure have been presented for different wave incidence angles in the frequency-domain. It has been shown that the peak period of $P_m$ for the optimum damping parameter coincides with the peak period of the time.mean wave drift force when ${\gamma}=0$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.299-306
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• 1989

The combined convective heat transfer from vertical parallel plates with constant temperature has been studied by numerical method. The governing equations for the system are solved by the finite difference method and successive over relaxation scheme for Re$_{L}$ = 50 - 500, Gr = 10$^{4}$, Pr = 0.7. Results for various plate spacings and plate lengths are as follows ; For various plate spacings, the mean Nusselt number increases and then decreases as the dimensionless plate spacing increases. The optimum plate spacing for maximum mean Nusselt number decreases with increasing Reynolds number and can be expressed as a function of Reynolds number. For various plate lengths, the mean plate Nudest number increases as the dimensionless plate length decreases and Reynolds number increases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.373-376
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• 2005

In recent years, there has been a growing need fur productivity improvement of ACS wire (Aluminum clad Steel wire) In optical communication market. So, it is necessary to improve the production speed and following quality of ACS wire to reduce the unit cost of the products. In this study, the pre-heating temperature and cladding speed is chosen as the factors can influence the mechanical and metallurgical properties during cladding, and the changing behavior of mechanical property and microstructure by controlling above two factors are investigated. And the bearing length and approach angle in cladding die are selected as the important elements for designing optimum die enabling high speed cladding. So we carried out FE(Finite Element) analysis using the above two elements as variables. This paper aims to understand the change of mechanical properties and microstructure according to the change of each factor during cladding and suggest the optimized cladding condition to get the best quality of OPGW. And also we would like to introduce the optimum die structure that enables high-speed cladding.

• Journal of the Korean Society of Clothing and Textiles
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• v.8 no.1
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• pp.39-45
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• 1984

The effects of Temperature on the removal of triglyceride were studied with soaps having various chain lengths of alkyl group. Cellophane, polyester film and alkali-treated polyester film were soiled with tripalmitin, tagged with 0" and detergency was evaluated by analysing the tripalmitine on the fabric before and after washing by means of liquid scintillation counting. The results were as following: 1) Triglyceride was completely removed from cellophane in distilled water without surfactant at any temperature, because of the hydrophillic nature of cellulose. The detergency of triglyceride from polyester film fully depended on the state of tripalmitin. The detergency of alkali treated polyester film was better than that of untreated polyester film at lower temperature due to increased hydrophillcity, but worse at higher temperature due to the diffusion of molten tripalmitin into the grooves, formed by alkali treatment. 2) The detergency from polyester film was increased with elevating temperature and after reaching some optimum detergencies, the detergencies were rather decreased with increasing temperature. The temperatures of optimum detergency were shifted to higher with increasing chain length of alkyl group. 3) When the soiled film was baked at $60^{\circ}C$ and $70^{\circ}C$ for 20 min, the detergency vs. temperature was much the same as the case of without-baking. These results indicate that the detergency of triglyceride was largely correlated with the suspending power of surfactants at low temperature and with state of soil and hydrophilicity of substrates with elevating temperature.

• Journal of Ginseng Research
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• v.6 no.2
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• pp.168-203
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• 1982

Effects of soil moisture on growth of Panax ginseng, of various factors on soil moisture, and of moisture on nutrition, quality, physiological disorder, diseases and insect damage were reviewed. Optimum soil moisture was 32% of field capacity with sand during seed dehiscence, and 55-65% for plant growth in the fields. Optimum soil moisture content for growth was higher for aerial part than for root and higher for width than for length. Soil factors for high yield in ginseng fields appeared to be organic matter, silt, clay, agreggation, and porosity that contributed more to water holding capacity than rain fall did, and to drainage. Most practices for field preparation aimed to control soil moisture rather than nutrients and pathogens. Light intensity was a primary factor affecting soil moisture content through evaporation. Straw mulching was best for the increase of soil moisture especially in rear side of bed. Translocation to aerial part was inhibited by water stress in order of Mg, p, Ca, N an Mn while accelerated in order of Fe, Zn and K. Most physiological disorders(leaf yellowing, early leaf fall, papery leaf spot, root reddening, root scab, root cracking, root dormancy) and quality factors were mainly related to water stress. Most critical diseases were due to stress, excess and variation of soil water, and heavy rain fall. The role of water should be studied in multidiciplinary, especially in physiology and pathology.

• Journal of Powder Materials
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• v.25 no.1
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• pp.48-53
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• 2018

One-dimensional rutile $TiO_2$ is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for $TiO_2$ nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of $TiO_2$ nanowires on a Ti alloy powder (Ti-6wt%Al-4wt%V, Ti64) using simple thermal oxidation under a limited supply of $O_2$. The optimum condition for $TiO_2$ nanowire synthesis is studied for variables including temperature, time, and pressure. $TiO_2$ nanowires of ${\sim}5{\mu}m$ in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of $TiO_2$ nanowires is greatly influenced by synthesis temperature and pressure. The synthesized $TiO_2$ nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).

• Proceedings of the Korean Institute of Interior Design Conference
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• 2001.05a
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• pp.117-120
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• 2001

This study is a preliminary research to develop design principles for environmentally friendly housing. The purposes of study are to investigate the literatures related passive design for summer and theory of ventilation, to analyze the indoor airflow patterns in traditional Korean house during summer, and to propose the design factors for effective passive cooling system. The analysis for airflow patterns was focused on the ‘An bang’and the ‘Dae Chung’in the ‘An Chae’of a traditional house located in Seoul. Field measurements of air temperature and air velocity were carried out at 30 different measuring points with 8 different window-opening conditions. The measurements were taken on the hottest summer days in August 2000. It is concluded that from an environmentally friendly standpoint design factors to control indoor thermal environment by a passive cooling system during the summer are as follows; ceiling structure has thermal performance like a time-lag effect, optimum height and length of eaves which can prevent sunlight and divert airflow toward the sitting level, building arrangement acceptable the prevailing wind, strategic window arrangement which makes cross ventilation possible (especially north-south) at the sitting level, window opening condition which is possible to intersect two cross-ventilation stream at the main living areas, northward windows remaining in shade to create the air pressure difference, and planning building shape like a bracket that has optimum width and depth.