• The Korean Journal of Ecology
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• 제15권4호
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• pp.395-410
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• 1992

Disturbance regime and tree regeneration were studied in kwangnung natural forest, an old-growth deciduous hardwood forest located in central korea. This forest is dominated by carpinus laxiflora, c.erosa, and quercus species. The area occupied by canopy gaps was 4.6% of the total forested area, and the mean size of canopy gaps was 92 $m^2$ with the maximum being 524 $m^2$. More than half of the gaps were less than four years old, and 3/4 of the gaps were created by death of only or two canopy trees, indicating the dominance of small-sized gaps in kwangnung forest. about half of the gap-makers were c. laxiflora, and another one third were quercus species. In contrast, the most frequent relacers were c. laxiflora while quercus species filled only 5% of the gaps, suggesting a future shift in tree species composition under the current disturbance regime. tree regeration was more conspicuous even in small gaps than non-gaps regardless of shade-tolerance of tree species, indicating the importance of gaps in tree regeneration.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.613-618
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• 2004

CCS was developed and applied to rotating machines because of accurately measuring the spindle error motion without significant efforts. However, researches on the CCS have been focused on ideal cases where circumferential gaps were ignored. This paper presents the effects of circumferential gaps and proposes an optimal CCS considering the circumferential gaps. First, electrostatic analysis of the CCS that includes the circumferential gaps is performed using the FEM, and an additional capacitance due to the circumferential gap can be approximated as an equivalent extended sensor length. Second, a mathematical model of the CCS considering the circumferential gaps is derived, and the optimal CCS is determined through minimization of the weighted error amplification factor. Finally, two CCSs, both considering and ignoring the circumferential gaps, are built, and the effectiveness of the optimal design is verified through simulation and experiment.

• Journal of the Korean Data and Information Science Society
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• 제25권5호
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• pp.1117-1125
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• 2014

In a longitudinal study, subjects can experience same type of events repeatedly. Also, there may exist intermittent dropouts resulting in repeated observation gaps during which no recurrent events are observed. Furthermore, when such observation gaps have incomplete forms caused by the unknown termination times of observation gaps, ordinary approaches result in biased estimates. In this study, we investigate the effect of ignoring observation gaps and propose methods to overcome this problem. For estimating the distribution of unknown termination times, an interval-censored mechanism is applied and two cases are considered. Simulation studies are carried out to evaluate the performance of the proposed method. Conviction data of young drivers with several suspensions are analyzed to illustrate the suggested approach.

• Agribusiness and Information Management
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• 제10권1호
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• pp.1-15
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• 2018

Many paddy cultivating farmers in the country are forced to use their limited resources to produce adequate food for their family, leading to the degradation and reduction in potential of these resources. The yield levels of paddy at the farmers' level and in the Front Line Demonstrations (FLDs) conducted in the farmers' fields is not at par with potential yield of the paddy variety. The gap between potential yield of crop variety and yield realized in FLDs refers to Research gap and the yield gap between FLDs and due to farmers' practice refers to Extension gap. The earlier studies conducted in India in general and in Andhra Pradesh in particular highlighted the existence of both research and extension gaps with reference to paddy. It is essential that, the narrowing of both research and extension gaps is not static, but dynamic considering the influence of technological interventions in boosting paddy yields at FLDs level and at farmers' level and also with the improvement of the yield potential of paddy varieties. This calls for integrated and holistic approaches to address these two gaps and with this background, the researcher aimed at this in depth study. The findings revealed that, research gaps are high with reference to weed management and pest management and extension gaps are high with reference to farm mechanization followed by fertilizer management. Reliable source of seed, capital use and frequency of meetings with Scientists or Agricultural Officers significantly influence the extension gaps in paddy. Farmers also prioritized socio-economic and technical constraints and the analysis infers that, it is high time now for the farmers to adopt the planned technological interventions on scientific scale to minimize the extension gaps to the extent possible. As the enabling environment in the State of Andhra Pradesh is highly encouraging for the farmers with relevant policy instruments in the form of subsidized inputs, free power, credit at concessional rates of interest, constructing irrigation projects etc., the adoption of the proposed technological interventions significantly contribute to minimizing both research and extension gaps in paddy cultivation in Kurnool district of Andhra Pradesh.

• 한국자동차공학회논문집
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• 제25권1호
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• pp.28-34
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• 2017

The vehicle stabilizer link is one of the suspension components that reduces the bumping and rolling during vehicle driving. However, this stabilizer link could be a source of the abnormal noises when its free gaps have higher than normal values. Therefore, the current study aims at investigating the quantitative relationships between the abnormal noises and free gaps of the vehicle stabilizer links, as well as the length of time that the vehicle stabilizer links could be used without generating abnormal noises. In this study, the abnormal noises were measured based on the magnitude of the stabilizer link vibration, while the free gaps were quantified through the force-displacement curves of the stabilizer links. Harsh durability tests were also conducted in order to quantify the operating cycles of the stabilizer links before generating the abnormal noises, along with the concomitant measurements of the free gaps. The current results showed that the abnormal noises of the stabilizer links were detected when its free gaps were larger than 0.12 mm. However, the free gaps of the stabilizer links, which are bigger than 0.1 mm, produced the abnormal noises at 1.5 million cycles under harsh durability test conditions. A parametric study in the future that would reflect the different shapes and sizes of the stabilizer links for diverse vehicles could determine more generalized relationships between the abnormal noises and free gaps of the vehicle stabilizer links.

• Communications for Statistical Applications and Methods
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• 제2권2호
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• pp.184-197
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• 1995

An objective and one-step detection procedure of multiple outliers is suggested by using the gaps of the order statistics. The detection procedure can be used as a routine outlier detection method of a statistical analysis computer program. The procedure is applied to some examples including the data selected by Kitagawa.

• 유공압시스템학회논문집
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• 제2권4호
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• pp.23-29
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• 2005

In order to improve the efficiency of hydraulic gear pumps or motors especially for high operating pressure, power losses due to viscous friction and leak flow through gear teeth end-gaps are considered in this paper. Optimal gaps minimizing the power loss for pumps and motors with uniform heights of gaps are analysed first. And the effect of the shapes of gaps with unequal heights on the power loss are studied and discussed by simulation. Considering that the outer shell lacing gear teeth may expand due to high internal pressure or thermal stress, the results drawn in this paper can be used for the design of high efficiency pumps and motors.

• Journal of Welding and Joining
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• 제9권4호
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• pp.40-49
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• 1991

Both impact and fracture toughnesses were investigated with root gaps in FCAW weld metals at room temperature and 0.deg.C. The maximum impact value was obtained at the root gap of 16mm for 1G position weld metal, and the impact value of 3G position weld metals also showed the maximum impact value at the root gap of 12mm. However, the fracture toughnes(CTOD)values tend to decrease with increasing root gaps at both temperatures in 1G weld metal. Bending test also showed satisfactory results with all of root gaps investigated. Based on this result, it becomes possible to apply wide root gaps in real projects in both aspects of toughness and bending resistance.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.299-315
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• 2016

In this work, a strategy for passive vibration control of periodic structures is proposed which involves adding a periodic array of simple resonant devices for creating band gaps. It is shown that such band gaps can be generated at low frequencies as opposed to the well known Bragg scattering effects when the wavelengths have to meet the length of the elementary cell of a periodic structure. For computational purposes, the wave finite element (WFE) method is investigated, which provides a straightforward and fast numerical means for identifying band gaps through the analysis of dispersion curves. Also, the WFE method constitutes an efficient and fast numerical means for analyzing the impact of band gaps in the attenuation of the frequency response functions of periodic structures. In order to highlight the relevance of the proposed approach, numerical experiments are carried out on a 1D academic rod and a 3D aircraft fuselage-like structure.

• 한국경제지리학회지
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• 제18권2호
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• pp.152-167
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• 2015

본 논문은 세계화가 지역의 성장격차에 미치는 영향을 분석하였다. 본 연구에서는 우리나라 16개 광역자치단체를 대상으로 무역의존도와 외국인직접투자를 세계화변수로 정하였으며 그 변수들이 지역간 성장격차에 미치는 영향을 분석하였다. 추정 결과 지역간 성장격차에 있어서 외국인직접투자가 유의한 영향을 미쳤으며 무역의존도(개방도)는 격차에 유의한 영향을 주는 변수가 되지 않는 것으로 나타났다. 연구결과 우리나라에서 지역갈등의 원인이 되고 있는 지역간 성장격차를 해소하고 균형적인 성장을 기하기 위해서는 취약지역에 외국인투자 특히, 신산업분야의 국내외투자를 적극 유치하는 것이 필요하다는 것을 보여주고 있다. 이에 따라 그동안 외국인직접투자를 지역발전정책의 수단이기 보다는 주로 외자유치차원에서 관심을 가져왔으나, 앞으로는 지역격차의 시정을 위한 중요한 정책수단으로 활용할 필요가 있다.