• Fisheries and Aquatic Sciences
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• v.12 no.2
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• pp.111-117
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• 2009

To develop sustainable management strategies for oyster farms in Pukman Bay, Korea, we estimated primary production using a numerical model. Because oysters are filter feeders, estimations of primary production (PP) are essential in developing management strategies. The daily PP ranged from 0.07 to 1.5 gC/$m^2$/d and showed significant spatial variations. The spatial distribution of PP was strongly associated with hydrodynamic features, and distinct patterns were observed in three different regions. In the inner bay, high PP was directly influenced by urban and agricultural sewage. The middle part of the bay had low PP, whereas PP in the outer area was high. PP was relatively low during the main oyster growth season, from late autumn to early winter. These findings represent important information for developing a management model for oyster farms in Pukman Bay.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.71-77
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• 2007

In case of the welding process, a conventional production method of gate valve, it has a merit of light weight, but also a demerit of high production cost and an impossibility in mass production due to work by hand. However, in case of the forging process, it has economic merits and can take a mass production process, too. The main focus of this paper is the optimization of preform in the forging process. This paper proposed an optimal design to improve the mechanical efficiency of gate valve made by forging method instead of welding. the optional design is conducted as application of real response model to Kriging model using computer simulation. Also, from verification of the response model with optimized results we were confirmed that the applications of Kriging method to structural optimum design using finite element analysis and equation are useful and reliable.

• Korean Journal of Pharmacognosy
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• v.22 no.2
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• pp.91-94
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• 1991

Callus was derived from the seedlings of Agastache rugosa(Labiatae). The growth rate of callus and the production of essential oil were studied with the variation of culturing conditions. 2, 4-D 2ppm in the medium was more effective for the production of essential oil than NAA 2ppm. The growth rate of callus and the production of essential oil were inhibited by the illumination of the light. The essential oils from Agastache rugosa and the callus cultivated on the medium containing 2, 4-D 2 ppm and kinetin 0.2 ppm were analysed by TLC, gas chromatography and mass spectrometry. These two oils showed different compositions. The main component of the plant oil, methyl chavicol was not contained in the callus oil.

• The International Journal of Costume Culture
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• v.13 no.1
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• pp.23-25
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• 2010

Archaeological evidence shows that cotton fibres of the genus Gossypium were first used for textile production at Mehrgarh, Pakistan in the Neolithic period ($6^{th}$ millenium BC). Eventually the cotton plant and textiles found their way to Egypt and through there, to Greece. However, the chronological origins of the cultivation and/or use of cotton fibres in textile production in ancient Greece are ambiguous. The main sources of information are ancient written texts and excavated textile finds. Both indicate that the introduction of cotton in Greece can be placed in the mid-first millenium BC. However, it is not clear whether the cultivation of the plant and consequently the production of cotton textiles was established in that period or whether another cotton species was produced and used locally in Greece or whether isolated examples of cotton textiles had been imported in Greece before the cotton plant. A more comprehensive analytical study of surviving textile finds coupled with archaeological research for plant production and cultivation would provide the answer to these questions.

• Speech Sciences
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• v.13 no.2
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• pp.107-120
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• 2006

The main purpose of this study is to investigate whether Korean learners can use the vowel duration cue to distinguish voicing contrasts in word-final consonants in English. Given that the Korean group's performance on the auditory task was much better than their performance on the identification task or on the production task, we conclude that the AX discrimination task makes contact with a different layer of perception. In particular, the AX discrimination task can be done at the auditory or phonetic level, where differences in vowel length are still encoded in the representation. In contrast, the identification and production tasks are probing the mental representation of vowel length and voicing. It was also founded that Korean speakers stored neither vowel length nor voicing in memorized representations and did not internalize the lengthening of the preceding vowel as a rule to differentiate the voicing contrasts of final consonants, even though they were able to detect the acoustic differences in vowel duration provided that they were tested in an appropriate task.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.591-603
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• 1999

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs a computer-aided process planning system for non-axisymmetric motor frame products with elliptical shape. The system developed consists of three modules. The first one os a 3-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. Especially, drawing coefficient, punch and die radii are considered as main design parameters. The constructed system for elliptical deep drawing products would be very useful to reduce lead time and improve accuracy for production.

• The Journal of Fisheries Business Administration
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• v.24 no.2
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• pp.69-82
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• 1993

The purpose of this paper is to estimate production function in the coastal fishing, especially long bag set net fishing and trap fishing using Cobb-Douglas production function with the three main variables: fishing quantity per tonage(WQFP), the number of working persons per tonage(WEMP), and the number of utilized fishing equipments per tonage(WEQU). The statistical results of such estimation reveal that fishing quantity per tonage can be expressed as a function of the number of working persons per tonage and the number of utilized fishing equipments per tonage. The estimated coefficients of WEMP and WEQU are statistically significant and also satisfy the requirements of Cobb-Douglas production function. This study also estimates marginal rate of technical substitution of labor in terms of capital (MRT $S_{LK}$ )in each long bag set net fishing and trap fishing. The resuits of this study show us that trap fishing has the technical characteristic of constant returns to scale(CRS) but long bag net fishing has that of decreassing returns to scale(DRS).

• Fibers and Polymers
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• v.3 no.4
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• pp.134-139
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• 2002

Carbon nanotubes are graphene sheets rolled up in cylinders with diameter as small as 1nm. Extensive work carried out in recent years has revealed the intriguing properties of this novel material. Exceptional property combined with low density of nanotubes makes them suitable for use as reinforcements in composites. Low volume of production and high cost is the main limitations towards their growth and application. Nanofibres bridge the gap between the conventional carbon fibre and the carbon nanotubes. With their low cost & comparatively higher volume of production along with their exceptional properties, the nanofibres are considered attractive material as nanoscale reinforcement. In this article a concise review of structure, property. production and application of carbon nanotubes and nanofibres have been discussed.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2184-2186
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• 2005

Neutron production is very important to apply fusion energy through SCBF(Spherically Convergent Beam Fusion) device and its rate is Proportional to the square of the ion current$({\propto}I^2)$. Also the ion current has a close relation with the potential well structure in grid cathode. In this paper, the ion current is calculated for the increasement of neutron production rate in a variety of grid cathode geometry. The atomic and molecular collision are taken into account by Monte Carlo Method and Potential is calculated by Finite Element Method. Main processes of the discharge is the ionization of $D_2$ by fast $D_2^+$ ion. As the number of a cathode ring is small and gap distance decreases, the ion current increases and neutron production rate will increase.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.1-14
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• 2010

Bio-ethanol is a promising alternative energy source for reducing both consumption of crude oil and environmental pollution from renewable resources like lignocellulosic biomass such as wood, forest residuals, agricultural leftovers and urban wastes. Based on current technologies, the cost of ethanol production from lignocellulosic materials is relatively high, and the main challenges are the low yield and high cost of the hydrolysis process. Development of more efficient pretreatment technology (physical, chemical, physico-chemical, and biological pretreatment), integration of several microbiological conversions into fewer reactors, and increasing ethanol production capacity may decrease specific investment for ethanol producing plants. The purpose of pretreatment of lignocellulosic material is to improve the accessible surface area of cellulose for hydrolytic enzymes and enhance the conversion of cellulose to glucose and finally high yield ethanol production which is economic and environmental friendly.