• Journal of Plant Biology
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• v.33 no.2
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• pp.147-150
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• 1990

Different species with similar niches can coexist in the same community if disturbances prevent compeptitive exclusion of competitively inferior species. Disturbances which open up gaps are common in all kind of community. Even in virgin forests without any artificial disturbance, there exist a significant proportion of trees of early successional shade-in-tolerant species in addition to the dominant late successional shade-tolerant species. In forest ecosystems, most canopy tree species including shade-tolerant ones require one or more gaps in their life-time to reach the canopy. Because of these frequent disturbances, forests can be considered of dynamic mosaics of patches of different ages and with different species composition which are in certain stages of recovery from disturbances. Disturbances temporarily increase the availability of resources such as light, water and soil nutrient for other in dividuals through the death of one or more canopy trees.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.483-487
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• 1994

In this paper, we analize the effect of a steering water used in a unified phase I-phase II semi-infinite constrained optimization algorithm and present a new algorithm based on the facts that when the point x is far away from the feasible region where all the constraints are satisfied, reaching to the feasible region is more important than minimizing the cost function and that when the point x is near the region, it is more efficient to try to reach the feasible region and to minimize the cost function concurrently. Also, the angle between the search direction vector and the gradient of the cost function is considered when the steering parameter value is computed. Even though changing the steering parameter does not change the rate of convergence of the algorithm, we show through some examples that the proposed algorithm performs better than the other algorithms.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.317-322
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• 2015

A process for the concurrent welding and extruding of pipe was designed for continuous production of fin tubes. Unlike a conventional pipe extrusion, the new process is able to extrude a pipe continuously without limit of length by using spring type wire material. The current paper provides the basic research for welding during the extrusion using a spring type wire material. The object of the current study is to investigate the possibility that the spring type wire material could be extrude into a welded pipe. The appropriate extrusion ratio was selected through investigation of loads using computer simulations. As a result, experiments showed that pipe could be welded and simultaneously extruded with spring type wire material of aluminum. The tensile strength of the welded and extruded aluminum pipe can reach 80% of tensile strength of original aluminum feedstock.

• Journal of Ocean Engineering and Technology
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• v.34 no.1
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• pp.13-18
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• 2020

An azimuth propeller can generate thrust in all directions by rotating its housing with an electric motor. An azimuth propeller can be operated using several methods to stop a ship. This study aims to derive an efficient method to stop a ship safely using an azimuth propeller through full-scale maneuvering trials with the research vessel "NARA" of Pukyong National University in 4.63 m/s (9 kts). Five methods with different azimuth propeller operations were tested to stop the ship. The test results confirmed that the simultaneous use of the thrust and the hydrodynamic force acting on the strut is the most effective method to stop the ship.

• KIEAE Journal
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• v.7 no.4
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• pp.81-89
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• 2007

The changes of social climate in respecting differences and needs of each diverse groups and human equality have caused the disabled to persue quality of life, through enabling their lives more independent. The purpose of this research was to find out adequacy of the residence and living behavior of the hearing impaired. Though this reach it was expected to find out environment features which have become obstacle in maintain their life independent in normal way and the way of improving their environment. Small group workshop with three hearing impaired persons was implemented. Living behavior and physical environmental characteristic of dormitory and interaction between them were identified. The need of non auditorial communication for the hearing impaired found far beyond required guidelines of the disabled Act. Design professionals need more profound knowledge with and ethical and humanistic attitude to find and satisfy the need of disabled.

• Journal of The Korean Association of Information Education
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• v.10 no.1
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• pp.83-90
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• 2006

Ability to find some information is the basic ability in information making activity. Even though students have been instructed how to search information, however, they don't reach a certain level. For improving ability to make information, it needs to be connected to Korean and Social education. Therefore, this paper analyzes the contents of related-subjects to internal and external curriculum of computer education, and develops the program to improve ability to make information, selecting learning point for improving ability to make information.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.25-32
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• 1984

Anterior spacing is one of the interesting phenomena in clinical orthodontics and presents difficulties in determining the etiology and the retention method. Only through the careful examination can orthodontists reach the correct diagnosis and treatment plan and every orthodontist should get rid of the cause to obtain good results. The author considered about the treatment and the retention method of the anterior spacing according to etiology and presented two eases of anterior spacing. In the first ease, the etiology was simple arch length discrepancy with excessively protruded anteriors. In the second ease, the etiology was the same as the above but the patient had the tongue thrusting habit. Both the eases showed the thin fibrous tissue bands between the upper central incisors but only the second case was thought to be associated with this tissue. The permanent retention loop which is non-surgical was applied to the ease and the results were acceptable.

• Structural Engineering and Mechanics
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• v.31 no.3
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• pp.297-314
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• 2009

When the temperature of a structure varies, there is a tendency to produce changes in the shape of the structure. The resulting actions may be of considerable importance in the analysis of the structures having non-prismatic members. Therefore, this study aimed to investigate the modeling, analysis and behavior of the non-prismatic members subjected to temperature changes with the aid of finite element modeling. The fixed-end moments and fixed-end forces of such members due to temperature changes were computed through a comprehensive parametric study. It was demonstrated that the conventional methods using frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. The design formulas and the dimensionless design coefficients were proposed based on a comprehensive parametric study using two-dimensional plane-stress finite element models. The fixed-end actions of the non-prismatic members having parabolic and straight haunches due to temperature changes can be determined using the proposed approach without necessitating a detailed finite element model solution. Additionally, the robust results of the finite element analyses allowed examining the sources and magnitudes of the errors in the conventional analysis.

• Journal of the Korean Society for Railway
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• v.8 no.5
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• pp.477-482
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• 2005

Through a year's commercial operation, Korea High Speed Railway has solved defectives from several breakages at the beginning and is going into the stage of stable operation. Among issues, wheel wear becomes a matter of primary concerns in view of vehicle's stability and maintenance. It was understood as above that wear status has been improved in the test by which railway system including vehicles and tracks was stabilized during a year's commercial operation, comparing to that with excessive wear in the trial operation prior to opening to the public. To make out wheel's wear status and characteristics of equivalent conicity at present when the service has been introduced a year ago and the average cumulative mileage of vehicles reach almost 500,000km, wheel's wear types were analyzed with the current vehicles in service.

• Journal of Ginseng Research
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• v.9 no.1
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• pp.72-85
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• 1985

Attempts were made to see if feeding of ginseng ethanol extract could affect proper- ties of rat brain lactate dehydrogenase such as specific activity, heat stability, Km for substrate, inactivation by 3-bromopyruvate and trypsin, and immune response. The following results were obtained. Specific activity of LDH was observed to reach maximum in 5 month after birth and then decrease steadily. However, that of LDH from rat fed with ginseng ethanol extract was found in rat fed with ginseng ethanol extract. 3-bromopyruvate was shown to inactivate LDH-5 from old rat fed. Inactivation of LDH-5 by trypsin was remarkable in old rat fed. Km value for pyruvate in old rat fed was remarkably decreased. Cumulative results suggest that ginseng ethanol extract could affect conformational change of LDH responsible for altered properties through unknown mechanism.