• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.110-116
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• 2011

The current study investigated the friction property of angle and width effect for micro-scale grooved crosshatch pattern on SKD11 steel surface against bearing steel using pin-on-disk type. The samples fabricated by photolithography process and then these are carry out the electrochemical etching process. We discuss the friction property due to the influence of a hatched-angle and a width of groove on contact surface. We could be explained the lubrication mechanism for a Stribeck curve. So It was found that the friction coefficient depend on an angle of the crosshatch on contact surface. It was thus verified that micro-scale crosshatch grooved pattern could affect the friction reduction. Also, it is play an important a width of groove to be improved the friction property. I was found that friction property has a relationship between a width and an angle for micro-grooved pattern.

• Corrosion Science and Technology
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• v.3 no.3
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• pp.87-97
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• 2004

This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.1-7
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• 2014

We consider a human contact social network that has connections through cellphone addresses. To construct such a social network, we use real call records provided by a large carrier, and connect to each other if there exists a call record between any two cellphone users. Due to its huge amount of data, we down-sample it in a way that the smallest-degree nodes are removed, in turn, from the network. For a moderate size of the networks we show that the degree distribution of the network follows a power-law distribution via linear regression analysis, implying the so-called scale-free property. We finally suggest some alternative measures to analyze a social network.

• Tribology and Lubricants
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• v.20 no.5
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• pp.266-271
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• 2004

The aim of this paper is to investigate the effect of surface texturing on reduction friction and to understand the potential of friction reduction through micro-scale dimple to fabricate by photolithography on pin-on-disk test using flat-on-flat contact geometry. It was verify that the friction property with respect to the same pitch has been influence on the size of dimple under lubricated sliding contact. Also, we can recognize from Stribeck curve that the friction property has a connection with the size of dimple. It can explain a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. The friction property has been an effect on the size of surface texture on reduction friction, not only because the density of dimple, but also because the ratio of diameter/pitch. This ratio of approximately 0.5 recommend under the tested friction condition. It suggested that the ratio of d/p is an important parameter for surface texture design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.3
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• pp.94-99
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• 2011

Micro-scale surface pattern has an benefit of tribological application under lubricated sliding contact. Therefore, a special pattern, that has to reduce the coulomb friction under contact, is considered to be necessary for improved efficiency of machines. The current study investigated the friction property of angle effect for micro-scale grooved crosshatch pattern on bearing steel surface using pin-on-disk type. The samples fabricated by photolithography process and then these are carry out the electrochemical etching process. We discuss the friction property due to the influence of hatched-angle on contact surface. We could be explained the lubrication mechanism for a Stribeck curve. It was found that the friction coefficient depend on an angle of the crosshatch on contact surface. It was thus verified that micro-scale crosshatch grooved pattern could affect the friction reduction.

• Journal of Korea Water Resources Association
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• v.41 no.9
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• pp.873-884
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• 2008

In this study, rainfall quantile was estimated using scale invariance property of rainfall data with different durations and the applicability of such property was evaluated for the rainfall data of South Korea. For this purpose, maximum annual rainfall at 22 recording sites of Korea Meteorological Administration (KMA) having relatively long records were used to compare rainfall quantiles between at-site frequency analysis and scale invariance property. As the results, the absolute relative errors of rainfall quantiles between two methods show at most 10 % for hourly rainfall data. The estimated quantiles by scale invariance property can be generally applied in the 8 of 14 return periods used in this study. As an example of down-scaling method, rainfall quantiles of $10{\sim}50$ minutes duration were estimated by scale invariance property based on index duration of 1 hour. These results show less than 10 % of absolute relative errors except 10 minutes duration. It is found that scale invariance property can be applied to estimate rainfall quantile for unmeasured rainfall durations.

• Journal of the Korean Professional Engineers Association
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• v.16 no.2
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• pp.1-11
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• 1983

The resistance property of a high speed passenger craft (: "DOL-PIN HO" designed by the author in 1972) is investigated as follows; -. The Resistance property of the craft is determined by savitsky′s method and blount-Fox′s method. The theoretical results are also compared with the full scale data. The comparison reveals that the result when using blount/fox′s method are in much closer agreement with the full scale data than savitsky′s. -. The effects of ship speed on the positions of the center of pressure and of the longitudinal center of gravity (L.C.G.) are investigated. The investigation shows that the position of L.C.G. of the craft is almost constant although the ship speed is changed. -. The effect of transom flap on the Resistance property of the craft is studied using savitsky/brown′s method. From the study it is found that the resistance of the craft is decreased and hence speed gain (about 3% of the service speed) can be obtained, when using transom flap for the craft.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.6
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• pp.898-908
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• 1999

This paper was aimed to identify the hand and sensibility of silk woven fabrics for neckties to find their relationships to the hand and purchasing preferences and to make their image scale. 56 male and female students evaluated 20 specimens with semantic differential scale of 21 hand and 25 sensibility adjectives. Data were analyzed through factor analysis pearson correlational coefficient t-test using PC SAS package. the hand adjectives were grouped as 4 surface property thermal property flexibility and dryness. The sensibility adjectives were modern classic character and natural,. The flat fabrics with warm hand displayed 'modern' sensibility but those with col hand show 'classic' The rough fabrics with warm hand showed 'natural' but those with cool hand showed 'character' The fabrics rated as high hand preference and purchasing preference showed soft and flat hand occuring 'modern' and 'classic' sensibility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.754-764
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• 2016

To understand and analyze SNS(Social Network Service) two important classes of networks, small-world and scale-free networks have gained a lot of research interests. In this study, a generalized network generation method is developed, which can produce small-world network, scale-free network, or network with the properties of both small-world and scale-free by controlling two input parameters. By tuning one parameter we can represent the small-world property and by tuning the other one we can represent both scale-free and small-world properties. For the network measures to represent small-world and scale-free properties clustering coefficient, average shortest path distance and power-law property are used. Using the model proposed in this study we can have more clear understanding about relationships between small-world network and scale-free network. Using numerical examples we have verified the effects of two parameters on clustering coefficient, average shortest path distance and power-law property. Through this investigation it can be shown that small-world network, scale-free network or both can be generated by tuning two input parameters properly.

• Journal of the Korean Geographical Society
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• v.41 no.2 s.113
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• pp.195-211
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• 2006

During the 1986-1994 Uruguay Round negotiations under the General Agreement on Trade and Tariffs (later World Trade Organization), the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) was adopted by participating countries. TRIPS has not only allowed intellectual property to be introduced into international trade arenas, but also extended the scope of protection to biodiversity such as plant genetic material, arguing that intellectual property rights (IPRs) would help conserve biodiversity. In this paper, I aim to deconstruct the global IPRs regimes over biodiversity by adopting geographers' sensitivity to place and scale as an analytical window. By investigating how all the issues regarding IPRs over biodiversity that are raised by diverse disciplines, such as environmental ethics, environmental economics and political economy approach, are scale-related, I demonstrate how biodiversity IPRs, and its introduction into international trade agreements, though separate issues with no inevitable relationship to one another, have been put together for the construction of global IPRs regimes. I argue that the notion on the construction of scale (i.e., rhetorical and discursive construct of globalization) can contribute to revealing how fragile global environmental conservation regimes are.