• Journal of the Korean Wood Science and Technology
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• 제50권1호
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• pp.68-80
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• 2022

Timber boardwalk decks are widely installed in parks and scenic areas to provide pedestrians an elevated footpath as well as harmony with the surrounding natural scene. In order to extend the lifespan of boardwalks in the outdoor environment, industrially treated pine timber, such as Pinus sylvestris, is often adopted. However, accidents of pedestrians injured by damaged boardwalk decks have been constantly reported. Therefore, the mechanical behavior of two different types of treated timber was examined in this study under repeated wetting and drying. An increasing number of radial cracks appeared with increasing length and width as more cycles were performed. A loss of more than 40% of the screw withdrawal capacity was observed in both end grain and face grain for the two types of timber after twelve accelerated wet-dry cycles, which coincides with the observation of damaged timber boardwalks in the field investigation. At the same time, it was found that both the compressive and the flexural strength was not sensitive to the wet-dry cycles especially at large cycle numbers.

• Annals of Fuzzy Mathematics and Informatics
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• 제16권3호
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• pp.301-316
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• 2018

In this paper, the concept of connected geodesic number, $gn_c(G)$, of a fuzzy graph G is introduced and its limiting bounds are identified. It is proved that all extreme nodes of G and all cut-nodes of the underlying crisp graph $G^*$ belong to every connected geodesic cover of G. The connected geodesic number of complete fuzzy graphs, fuzzy cycles, fuzzy trees and of complete bipartite fuzzy graphs are obtained. It is proved that for any pair k, n of integers with $3{\leq}k{\leq}n$, there exists a connected fuzzy graph G : (V, ${\sigma}$, ${\mu}$) on n nodes such that $gn_c(G)=k$. Also, for any positive integers $2{\leq}a<b{\leq}c$, it is proved that there exists a connected fuzzy graph G : (V, ${\sigma}$, ${\mu}$) such that the geodesic number gn(G) = a and the connected geodesic number $gn_c(G)=b$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.190-195
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• 2004

The compression-compression fatigue properties of the closed cell Al-Si-Ca alloy foams have been studied. The monotonic and cyclic compressive properties were compared with each other and the fatigue stress-life (S-N) curves were presented. In compression-compression fatigue, the crushing was found to initiate in a single band which broadens gradually with additional fatigue cycles. Progressive shortening of the specimen took place due to a combination of low cycle fatigue failure and cyclic ratcheting which is in accordance with the findings of previous researchers [1-3]. Young's modulus of the foam was found to decrease with the increasing strain in case of fatigue test however in case of monotonic compression test the value of Young's modulus increased with the strain (number of cycles). The endurance limit on the basis of $10^{7}$ cycles obtained by extrapolating the experimental results were 0.98 MPa and 1.70 MPa for load ratios 0.1 and 0.5 respectively which are 34 % and 59 % of the plateau stress.

• 한국의류산업학회지
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• 제16권1호
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• pp.153-159
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• 2014

This study evaluates the changes of the subjective hand, preference, comfort and mechanical properties of tricot based artificial suede made from sea-island type micro fibers according to raising condition. The subjective hand and the preference of raised suede for jacket were rated by the 20's and 30's women experts according to raising cycles. Comfort properties were evaluated by air permeability, water vapor transmission, and thermal transmission. Mechanical properties were measured by the KES-FB system. The subjective hand of artificial suede was categorized into three hand factors: smoothness, warmness and thickness. Smoothness, warmness and thickness perception increased with raising cycles which affected hand preference and luxuriousness perception. The thickness and wale density of suede increased with the number of raising. Suede became more compact and less pliable and less stretchable due to increased fabric thickness; in addition, the surface of suede became smoother and compressive since the surface evenness of suede improved with smaller fiber fineness and an increased amount of naps covered the base fabric. Furthermore, water vapor transmission decreased and thermal insulation increased. The best raising conditions for artificial suede was four cycles in which artificial suede was preferred without changes in physical properties.

• 한국염색가공학회지
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• 제12권3호
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• pp.192-198
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• 2000

Influence of the fluorescent whitening agent(FWA)'s adsorption on the whiteness of cotton and on the color change of the dyed fabrics was investigated by repeating wash cycles. Cotton 100% and cotton60/polyester40 blended fabrics were dyed pink, blue and yellow, and cyanuric chloride diamino stilbene(CC/DAS) and distyryl bisphenyl(DSBP) were used for the FWA with laundry detergents. Fabrics were washed at $20^\circ{C}$ with Terg-o-tometer. The FWA adsorption amount was measured by the absorption intensity for the pyridine-water extracted solution. The FWA adsorption increased on the cotton fabric with the wash cycles. Though adsorption of CC/DAS continuously increased up to the 20th cycle, that of DSBP increased sharply before the 10th cycle and reached an equilibrium. The whiteness of the fabrics dried in the shade was greater than that dried under the sunlight through window glass. The color change of dyed fabrics was increased by the number of wash cycles. Pink changed more greatly than blue, yellow or grey cloth. The color change(\Delta{E)}$ of dyed fabric washed repeatedly up to the 20th cycle with the detergent without FWA was less than 1. It is recommended to wash pale colored fabric with the detergent free of FWA.

• The Plant Pathology Journal
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• 제32권3호
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• pp.260-265
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• 2016

We observed the changes in aggressiveness and fecundity of the anthracnose pathogen Colletotrichum acutatum on hot pepper, under the ambient and the twice-ambient treatments. Artificial infection was repeated over 100 cycles for ambient ($25^{\circ}C/400ppm$ $CO_2$) and twice-ambient ($30^{\circ}C/700ppm$ $CO_2$) growth chamber conditions, over 3 years. During repeated infection cycles (ICs) on green-pepper fruits, the aggressiveness (incidence [% of diseased fruits among 20 inoculated fruits] and severity [lesion length in mm] of infection) and fecundity (the average number of spores per five lesions) of the pathogen were measured in each cycle and compared between the ambient and twice-ambient treatments, and also between the early (ICs 31-50) and late (ICs 81-100) generations. In summary, the pathogen's aggressiveness and fecundity were significantly lower in the late generation. It is likely that aggressiveness and fecundity of C. acutatum may be reduced as global $CO_2$ and temperatures increase.

• 한국정보과학회논문지:시스템및이론
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• 제26권8호
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• pp.999-1007
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• 1999

이 논문은 재귀원형군 G(2^m , 2^k )를 그래프 이론적 관점에서 고찰하고 정점이 서로소인 사이클과 그래프 invariant에 관한 위상 특성을 제시한다. 재귀원형군은 1 에서 제안된 다중 컴퓨터의 연결망 구조이다. 재귀원형군 {{{{G(2^m , 2^k )가 길이 사이클을 가질 필요 충분 조건을 구하고, 이 조건하에서 G(2^m , 2^k )는 가능한 최대 개수의 정점이 서로소이고 길이가l`인 사이클을 가짐을 보인다. 그리고 정점 및 에지 채색, 최대 클릭, 독립 집합 및 정점 커버에 대한 그래프 invariant를 분석한다.Abstract In this paper, we investigate recursive circulant G(2^m , 2^k ) from the graph theory point of view and present topological properties of G(2^m , 2^k ) concerned with vertex-disjoint cycles and graph invariants. Recursive circulant is an interconnection structure for multicomputer networks proposed in 1 . A necessary and sufficient condition for recursive circulant {{{{G(2^m , 2^k ) to have a cycle of lengthl` is derived. Under the condition, we show that G(2^m , 2^k ) has the maximum possible number of vertex-disjoint cycles of length l`. We analyze graph invariants on vertex and edge coloring, maximum clique, independent set and vertex cover.

• 화약ㆍ발파
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• 제29권1호
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• pp.10-16
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• 2011

대규모 사면이나 암반구조물의 불안정한 지반을 새로운 평형상태로 유지시키기 위한 지보재로서 그라운 드 앵커, 케이블 볼트, 록 볼트와 최근 새로운 형태로 개발된 지보재인 스파이럴 볼트가 있다. 이에 본 연구에서는 현재 가장 널리 이용되고 있는 지보재인 록 볼트와 새롭게 개발되고 있는 스파이럴 볼트를 대상으로 터널 내 현장 인발시험을 수행하여 지보재의 특성을 분석하였다. 최대인발하중의 변화 양상을 살펴보기 위해 수행한 스파이럴 볼트와 록 볼트에 대한 3회 재인발시험의 결과를 보면 스파이럴 볼트의 경우는 인발시험 횟수에 관계 없이 거의 일정함을 보였는데, 이것은 지보재가 최대인발하중에 도달할지라도 스파이럴 볼트와 충전재 사이에 파괴가 거의 일어나지 않으므로 일정한 최대인발하중을 보이는 것으로 판단된다. 반면에 록 볼트의 경우 인발시 험의 횟수가 증가할수록 인발하중은 점점 감소하였는데, 이것은 지보재가 최대인발하중에 도달할 때 록 볼트와 충전재 사이에 일부분 파괴가 발생함으로 인해서 나타나는 현상으로 판단된다.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.5-10
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• 2003

In this study, a new programming method to minimize the generation of Si-SiO$_2$interface traps of SONOS nonvolatile memory device as a function of number of porgram/erase cycles was proposed. In the proposed programming method, power supply voltage is applied to the gate. forward biased program voltage is applied to the source and the drain, while the substrate is left open, so that the program is achieved by Modified Fowler-Nordheim(MFN) tunneling of electron through the tunnel oxide over source and drain region. For the channel erase, erase voltage is applied to the gate, power supply voltage is applied to the substrate, and the source and dram are left open. Also, the asymmetric mode in which the program voltage is higher than the erase voltage, is more efficient than symmetric mode in order to minimize the degradation characteristics or SONOS devices because electrical stress applied to the Si-SiO$_2$interface is reduced due to short program time.

• 한국주조공학회지
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• 제12권6호
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• pp.450-457
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• 1992

The study aims to investigate the influence of alloying elements(V,Ti) and heat treatment on the mechanical properties in hypo-eutectic chromium cast iron. Before heat treatment, all of the specimen were fully annealed(950$^{\circ}C{\times}5Hr$) to homogenize their structures. The influence of heat treatment and alloying elements(V,Ti) on hardness, retained austenite volume, and charpy impact energy as well as tensile strength of the specimen was tested systematically. Retained austenite decreased with the increase of V and Ti, but incresed with the increase of number of cycles. The impact energy decreased, and hardness and tensile strength increased with the increase of alloying elements (V,Ti) and the decrease of the number of cycles. The hardness and tensile strength increased, but impact energy decreased with the increase of V and Ti elements and the temperature of destabillization heat treatment. After the destabillization heat treatment at the same temperature, the impact energy is increased, while hardness and tensile strength decreased as the increase of tempering temperature. Retained austenite increased with increase of destabilizatoin heat treatment temperature, while decrease with the increase of tempering temperature.