• Structural Engineering and Mechanics
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• 제32권4호
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• pp.501-516
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• 2009

This paper aims to study the large deflections of variable-arc-length elastica subjected to the terminal forces (e.g., axial force and torque). Based on Kirchhoff's rod theory and with help of Euler parameters, the set of nonlinear governing differential equations which free from the effect of singularity are established together with boundary conditions. The system of nonlinear differential equations is solved by using the shooting method with high accuracy integrator, seventh-eighth order Runge-Kutta with adaptive step-size scheme. The error norm of end conditions is minimized within the prescribed tolerance ($10^{-5}$). The behavior of VAL elastica is studied by two processes. One is obtained by applying slackening first. After that keeping the slackening as a constant and then the twist angle is varied in subsequent order. The other process is performed by reversing the sequence of loading in the first process. The results are interpreted by observing the load-deflection diagram and the stability properties are predicted via fold rule. From the results, there are many interesting aspects such as snap-through phenomenon, secondary bifurcation point, loop formation, equilibrium configurations and effect of variable-arc-length to behavior of elastica.

• The Plant Pathology Journal
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• 제33권4호
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• pp.410-423
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• 2017

Pathological interrelations of two soil-borne diseases in cucurbits (watermelon, oriental melon, shintosa and cucumber) caused by Fusarium isolates (FI) and the root-knot nematode (RKN), Meloidogyne incognita were characterized by the fusarium disease severity index (DI), RKN gall index (GI) and eggmass index (EI) in inoculation tests using FI and RKN. Virulence of FI as determined by DI at 4 weeks after inoculation was mostly in the higher order of Fusarium proliferatum F6, F5 and Fusarium oxysporum f. sp. melonis or Fusarium oxysporum f. sp. niveum with no significant differential interactions among the cucurbits and RKN co-infection. Significant increases of DI due to RKN coinfection were noticed in watermelon and oriental melon infected with F. proliferatum isolates, suggesting the DI increase due to RKN coinfection may depend upon the virulence of FI relative to aggressiveness of RKN on the cucurbits. For the coinfection of FI and RKN, GI and EI were mostly reduced logarithmically with the increase of DI, largely more in EI than GI, in all cucurbits except for shintosa. Microscopic examination of the root tissues showed histopathological features characteristic to infection types; formation of fungal hyphae and/or spores and plant defense structures (tyloses and mucilage) in variable degrees and formation of giant cells at variable developmental stages and with variable cytoplasmic depletion or degeneration which were visualized in relations with the values of DI, GI and EI. These findings will be helpful to develop control strategies of the soil-borne disease complex based on their pathological characteristics.

• 한국의류학회지
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• 제20권5호
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• pp.753-768
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• 1996

The purpose of this study is to find out the effect of suit color, necktie color and necktie patterns on the men's suit image formation. The experimental materials developed for this study were a set of stimuli and response scales. The stimuli were 28 color pictures manipulated with suit color, necktie color and necktie patterns by computer drawing. The experimental design consists of 3 factorial design; 1) suit color (navy blue, beige), 2) necktie color (analogous, complimentary color), 3) necktie patterns (plain, dot, stripe, check, paisley, floral, abstract) The 7-point semantic differential response scale designed for visual evaluation of men's suit image on suit color, necktie color and necktie patterns were composed of 34 bipolar adjectives. The subject are 150 female undergraduate students in Chin-ju city. They responded twice to 14 stimuli at random order The result of this study are as follows; 1. By analyzing the responses of the subjects, 4 factors emerged in the dimensional structure of the men's suit image formed by suit color, necktie color and necktie patterns. The 4 factors are charm, potency, uniqueness and tenderness. Among these, charming and potential factors proved to be more important. 2. necktie color, suit color and neckite patterns had the significant effect on the formation of men's suit image. In the charm image, only necktie patterns were proved to be the most dominant variable. The most dominant variable in the potencial and unique image was necktie color and second to it suit color was important. But suit color was most significant in the image of tenderness. 3. In the effects of interactions between each variables, the combination of suit color and necktie color wins more significant than that of suit color and necktie patterns and that of necktie color and necktie patterns, but in the image of tenderness, only the combination of suit color and necktie color was more significant. In the interaction of suit color, necktie color and necktie patterns, the potential factor didn't have the significant effect.

• Journal of Welding and Joining
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• 제21권3호
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• pp.58-67
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• 2003

In this study, the formation mechanism of discontinuities in the laser fusion zone of diamond saw blade was investigated. $CO_2$ laser weldings were conducted along the butt between Fe base sintered tip and carbon steel shank with sets of variable welding parameters. The effect of heat input on irregular humps, outer cavity, inner cavity and bond strengh was evaluated. The optimum heat input to have a proper humps was in the range of 10.4~$17.6kJm_{-1}$. With increasing heat input, both outer and inner cavities were reduced. The outer cavity was caused by insufficient refill of keyhole, while inner cavity was caused by trapping of bubble in molten metal. The bubble came from sintered tip and intensive vaporization at bottom tip of the keyhole. A gas formation and low melting point element vaporization were not occurred during welding. We could not find any relationship between bond strength and amount of discontinuities. Because the fracture were occurred in not only sintered tip but also carbon steel shank due to hardness distributions.

• 한국의류학회지
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• 제28권3_4호
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• pp.460-471
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• 2004

The purpose of this study is to investigate the effect of hair-style (straight and wave), hair-length(short, medium, and long), and type of hat design (no-hat, beret, cloche, bowler, and capeline) on impression formation. The experimental materials developed for this study were a set of stimulus and response scales. The 7-point semantic differential response scales were designed. Thirty stimuli color pictures of various combination of hair length, hair style, and type of hat design were manipulated by computer drawing. The subjects were 360 undergraduates living in Seoul, Kyunggi and Kyungnam. The experimental design was composed of 3 factorial designs. The result of the study can be summarized as follows; Impression factor of the stimulus consisted of the 5 different dimensions (attractiveness, gracefulness, activity, concentration of attention, cuteness). Hair style greatly affected gracefulness. On the other hand, hair length made remarkable effects on attractiveness, concentration of attention, and cuteness. In addition, it has been found that the type of hat design significantly influenced on all the factors except attractiveness as independent variables. In regarding the effect of interaction between each variable, the combination of hair style and hair length had significant effects on gracefulness. In the impression formation of cuteness, the combination of hair length and type of hat design were more significant.

• Journal of Oral Medicine and Pain
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• 제25권1호
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• pp.53-62
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• 2000

Bone marrow culture systems are widely used to differentiate osteoclast-like cells in vitro using several osteotropic hormones. In this study, we isolated and cultured the mouse bone marrow cells with or without some osteotropic hormones such as parathyroid hormone(PTH), prostaglandin $E_2(PGE_2)$ and $l,25(OH)_2-vitamin$ $D_3$(Vit. $D_3$). We confirmed the formation of osteoclast-like cells morphologically and functionally by the expression of tartrate-resistant acid phosphatase(TRAP) and by their capability to resorb dentin slices. We also studied the effects of transforming growth $factor-{\beta}(TGF-{\beta})$ and epidermal growth factor(EGF) on the Vit. $D_3-induced$ osteoclast-like cell formation. In control, a few multinucleated cells were formed whereas PTH and $PGE_2$ increased the number of multinucleated cells. PTH, $PGE_2$ and Vit. $D_3$ induced the formation of TRAP-positive multinucleated cells. After culture of mouse bone marrow cells on the dentin slices with or without osteotropic hormones, giant cells with diverse morphology were found on the dentin slices under the scanning electronmicroscopy. After removing the attached cells, resorption pits were identified on the dentin slices, and the shape of resorption pits was variable. EGF increased the osteoclast-like cell formation induced by Vit. $D_3$, however, $TGF-{\beta}$ showed biphasic effect, which at low concentration, increased and at high concentration, decreased the osteoclast-like cell formation induced by Vit. $D_3$.

• 벤처창업연구
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• 제7권4호
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• pp.33-40
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• 2012

본 연구는 관광상품의 주요 구성요소인 여행사에 대한 경험이 PAD모형에 따른 소비자의 감성 형성에 미치는 영향과 소비자의 감성민감도가 여행사 경험에서 유도되는 감성에 대한 조절적 역할을 분석하였고 여행사 경험에서 유도된 감성이 여행사에 대한 소비자의 태도와 재구매의도 형성에 미치는 차별적 효과를 검증하였다. 실증자료 분석으로부터 다음과 같은 연구결과를 얻었다. 첫째, 중요한 여행사 경험요소로 반응성, 정중성, 업무수행능력, 차별성 등 네 요소가 식별되었고 이들이 소비자의 경험이 즐거움-각성-지배(Pleasure-Arousal-Dominance: PAD) 정서를 차별적으로 유도한다는 가정이 실증적으로 확인되었다. 둘째, 정서에 관련된 주요 개인차 변수의 하나인 감성민감도(Affect Intensity)가 여행사경험에서 유도되는 정서 형성에 조절적 영향을 미치는 것으로 확인되었다. 셋째, 여행사 경험에서 유도된 정서는 각각 여행사에 대한 소비자의 태도 형성과 재구매의도 형성에서 차별적 영향을 미친다는 가정 역시 검증되었다.

• The Plant Pathology Journal
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• 제21권4호
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• pp.322-327
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• 2005

Regression models for determining infection periods of apple white rot were developed based on conidial germination and appressorium formation of Botryosphaeria dothidea. A total of 120 apple fruits were inoculated with the fungal conidial suspension and subjected to 6 temperatures and 10 wetness periods. Conidia germinated and produced appressoria, exhibiting swollen tips of germ tubes on the fruit surface. Conidial germination (G) increased with temperature (T) and wetness period (W), and was described as $G=-89.273+7.649T+7.056W-0.109T^{2}-0.085W^{2}-0.066TW(R^{2}=0.75)$. Less than 2 hr of wetness period were enough for conidia to germinate at 25 to $30^{\circ}C$. Effects of temperature and wetness period on appressorium formation (A) could be explained as $A=-1.540-2.375W+0.045W^{2}+0.213TW(R^{2}=0.77)$. The relationship between conidial germination and appressorium formation ($A_g$) was described as$A_g=0.381-0.227G+0.005G^{2}(R^{2}=0.67)$, suggesting that conidial germination may have to reach approximately $43.7\%$ to initiate appressorium formation. Using the regression equation for conidial germination and the criterion of $43.7\%$ conidial germination, an infection model was developed to determine infection periods based on temperature and wetness period. The infection model with the criterion of $43.7\%$ conidial germination was apparently more conservative than the appressorium formation model in determining possibility of apple infection. The infection model seemed sensitive to variable weather conditions, suggesting possible use of the model for timing fungicide sprays to control white rot of apples in practice.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 춘계학술발표대회 개요집
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• pp.303-306
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• 2000

Quality estimation of the weld has been one of the important issues in RSW which is a main process of the sheep metal fabrication in auto-body industry, It was well known that among the various welding process variables, dynamic resistance has a close relation with nugget formation. With this variable, it is possible to estimate the weld quality in real time. In this study, a new quality estimation algorithm is developed with the primary dynamic resistance measured at welding machine timer. For this, feature recognition method of Hopfield neural network is used. Primary resistance patterns are vectorized and classified with five patterns. The network trained by these patterns recognizes the dynamic resistance pattern and estimates the weld quality Because the process variable monitored at the primary circuit is used, it is possible to apply this system to real time application without any consideration of electrode wear or shunt effect.

• 한국기계가공학회지
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• 제13권2호
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• pp.89-93
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• 2014

Variable polarity (VP) arc welding is known as an effective solution for aluminum thanks to the cleaning effect, which means oxide removal, during the DCEP (direct current electrode positive) period. In this research, VP GTAW (gas tungsten arc welding) is adopted for lap joint fillet welding of 3mm thickness 5052 aluminum alloy. Various welding currents and DCEP duty cycles are applied as welding conditions with a fixed welding speed to investigate the influence of DCEP characteristics on weld bead formation. Results show a tendency of higher heat input for higher DCEP duty cycle, which result does not follow conventional arc theory because it is known that DCEN (DC electrode negative) polarity is more efficient for heat input than is DCEP. This phenomenonhas recently been reported by several VP-GTA researchers and is still controversial because the mechanism of oxide removal is not yet clear except for the previous, well-known idea of "ion bombardment", which cannot explain the situation. Finally, proper usage conditions for VP-GTAW are suggested; then, further, related theoretical topics in the field of cathode physics are brieflyintroduced.