• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1084-1092
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• 2006

Shape optimization of airfoil in WIG craft has been performed by considering the ground effect. The WIG craft should satisfy various aerodynamic characteristics such as lift, lift to drag ratio, and static height stability. However, they show a strong trade-off phenomenon so that it is difficult to satisfy aerodynamic properties simultaneously. Optimization is carried out through the multi-objective genetic algorithm. A multi-objective optimization means that each objective is considered separately instead of weighting. Due to the trade-off, pareto sets and non-dominated solutions can be obtained instead of the unique solution. NACA0015 airfoil is considered as a baseline model, shapes of airfoil are parameterized and rebuilt with four-Bezier curves. There are eighteen design variables and three objective functions. The range of design variables and their resolutions are two primary keys for the successful optimization. By two preliminary optimizations, the variation can be reduced effectively. After thirty evolutions, the non-dominated pareto individuals of twenty seven are obtained. Pareto sets are all the set of possible and excellent solution across the design space. At any selections of the pareto set, these are no better solutions in all design space.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.662-666
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• 1996

The variations of the surface topographical parameters for the analysis of the pedestrian slip and fall accidents during the sliding friction between the specially prepared floor specimens and three working shoes were investigated. The profile ordinate data for each flooring specimen were obtained at 1.1 .mu.m intervals using a laser scanning confocal microscope system along to the direction of sliding. A number of surface roughness parameters, that is, the centre line average (c.l.a.) and root mean square (r.m.s.) roughness, maximum height (Rtm), maximum mean peak height (Rpm), maximum mean depth (Rvm), and average asperity slope were calculated using a computer program and compared with the dynamic friction results. The analysis showed that the surface parameters undergo marked variations during the sliding process, but the variations were statistically significant. It was found that amongst various surface parameters, the maximum depth (Rvm) and the average asperity slope of the asperities were the biggest variation during the sliding proceeding. This result confirms the previous study and may suggests a new approach to monitoring the flooring environments with their service as the effort to reduce the pedestrain slip accident.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.312-317
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• 2001

Modifying effects of the rectangular forward step for suppressing the unsteady pressure fluctuation during interaction between the upstream vortical flow with the edge are studied numerically. The vortical flow is modeled by a point vortex, and the unsteady pressure coefficient is obtained from the velocity and the potential field. To investigate the effects of the edge shape the rectangular forward step is chamfered with various angles. Calculation show that the pressure peaks become decreased by increasing the vortex height as well as the chamfering angle. The pressure amplitudes are very sensitive to the change of the initial vortex height. From this study we can find out that the chamfered edge has two effects; the one is that it suppresses the pressure amplitude generated from the edge, and the other is that it decreases the time variation of unsteady pressure fluctuation. These modifying concepts can be applied to attenuate the self-sustained oscillation mechanism at the open cavity flow.

• Journal of Life Science
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• v.8 no.5
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• pp.504-508
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• 1998

A study was conducted to evaluate a protein removal characteristics by foam separation. The foam separator was operated in well-mixed tank which would be considered as a completely mixed condition. The feasibility of foam separation to remove protein from fresh and sea water was investigated. Protein removal characteristics of the foam separator were obtained by batch reactor operations. To find the effect of the operating parameter to protein removal rate, the foam separation was carried with variation of initial protein concentration and foam height. The results indicated that the protein removal efficiency was increased with increasing protein concentration and decreased with increasing foam height. The relationship between protein concentration and protein removal rate was evaluated by linear regression.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.10
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• pp.1378-1385
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• 2002

The importance of direct genetic, maternal, heterosis and epistatic effects were examined on post-weaning weight, height, length, girth, fat depth and muscle (ratio of stifle to hip width) with dry and wet season gains in these traits. The breeds used were two pure breeds (Jersey and Limousin), the Limousin${\times}$Jersey $F_1$, and two backcrosses ($F_1{\times}$Jersey dams and $F_1{\times}$Limousin dams). Direct genetic effects were large (p<0.001) for all traits except for length. Jersey maternal effects were large for weight, girth, fat depth and muscle in the post-weaning wet season gains which is an evidence of the impact of Jersey dam on progeny beyond weaning. There were large heterosis effects on fat depth and muscle relative to other traits. Epistatic effects were observed for post-weaning performance in weight, girth, fat depth and muscle. There are indications that there were different genetic effects for post-weaning compared to preweaning growth traits. Thus, it could be hypothesized from this study that different quantitative trait loci (QTL) affect early and late growth in Jersey and Limousin cross cattle breeds. The follow up work will examine the different chromosomal gene effects on pre- and post-weaning growth.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.312-322
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• 1997

The natural convective flow in a two-dimensional square enclosure with horizontal partitions is investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and two identical partitions were positioned perpendicularly at the mid-height of the right and left walls, respectively. The governing equations are solved by using the finite element method with Galerkin method. Calculations are made for different partition lengths, partition conductivites, and Rayleigh numbers based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). An oscillatory motion of the natural convective flow is affected significantly by the variation of the gap width and Rayleigh number. When the gap width is comparatively short, the heat transfer rate is raised with the increase of the thermal conductivity of partitions. However, for sufficiently large gap widths at higher Rayleigh numbers, the average Nusselt numbers of the conductive partitions are smaller than those of the adiabatic partitions.

• Journal of Plant Biology
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• v.35 no.2
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• pp.125-134
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• 1992

Taxonomic account is given to the five species of Scytosiphonaceae, Colpomenia peregrina (Sauvageau) Hamel, Endarachne binghamiae J. Agardh, Hydroclathrus clathratus (C. Agardh) Howe, Petalonia fascia (O. F. Muller) Kuntze, and Scytosiphon lomentaria (Lyngbye) Link, collected from Ullungdo Island, Korea. C. peregrina, introduced for the first time in Korea, is similar to C. sinuosa (Roth) Derbes et SolieI in outer appearance but is distinguished by absence of cuticle over the plurilocular sporangial sori. E. binghamiae accords well with American plants but varies in height and width of the thallus according to seasons. H. clathratus has small cortical cells and large clear medullary cells. P fascia is characterized by one to two celled small cortical layer and two to four celled large medullary layer. S. lomentaria shows variation in gross morphology, especially in height and width of thallus according to seasons.easons.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.1 s.139
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• pp.91-102
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• 2005

The purpose of this study was to investigate the range of variation for commonly accepted ease in a business jacket and thus to find solutions to the problem of fit and ease in ready-to-wear jackets. This study was based on anthropometric measurements, pattern measurements, which were used to calculate ease amount according to each jacket part. The survey subjects were 493 males, between 25 to 59 years old, buying a jacket at stores in Seoul. In the results, the aesthetic purpose of a business jacket(custom-fit jacket) was clearly observed by the means of controlling the ease amount at chest, waist and hip. The ease at chest and waist(ready-to-wear) clearly revealed a difference among prototypes. This result can be explaned by the regular drops and the similar length-width proportions between sizes in ready-to-wear Jackets. Therefore, customers with varying body drop differences, who had to choose a homogeneous jacket drop, experienced too much ease at the Waist and Hip compared with custom-fit customers. In addition, the height could be an integral factor to affect the ease of jacket length and sleeve length. The ease at these parts was significantly different among height groups and showed negative relationships.

• Ecology and Resilient Infrastructure
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• v.4 no.4
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• pp.245-254
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• 2017

In this study, the flow characteristics and bed changes in the upstream and downstream of weirs with the variation of the weir angels are investigated quantitatively through the laboratory experiments. As the angle of weir increases, the effective weir length decreases. Delta is developed by the sediments inflow upstream and migrates downstream. Delta migration speed decreases as it approaches to the weir upstream, and the size is getting big. As the dimensionless weir length increases, the dimensionless wave length decreases at the downstream of the weir. However, the dimensionless bar height decreases. The dimensionless wavelength increases with the bar height downstream from the weir.

• Journal of the Korean Society of Costume
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• v.42
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• pp.223-230
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• 1999

Dressmaking which is defined as the process of changing two-dimensional cloth into three-dime-nsional clothes needs a lot of joining parts. Particularly sleeve needs a more curved surface than other joining parts owing to shape of the top of arms. Easing is used to control the fullness along the seam-line to create the fullness curved shape of the sleeves and it plays an important role in increasing three-dimensional constru-ction power. unfortunately sufficient data regarding effective easing conditions to increase three-dimensional construction power of sleeve are not available. Therefore the author tried to investigate the effective easing conditions to increase three-dimensional construction power of sleeve by cap height. Easing construction power of sleeve by cap height. Easing contraction made by different angles on the sleeve cap curve line previous work were examined and the effective easing conditions according to the variation of angles were determined. This study contains the following objectives. Firstly to obtain the easing contraction ratio in sleeve according to the above easing conditions. Secondly to investigate the three-dimensional construction power or sleeve by the factors of easing contraction. Thirdly to determine for each sleeve the effective easing conditions on the basis of the calcuative easing contraction ratio in the sleeve patterns by cap heights.