• Journal of the Korean Regional Science Association
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• v.32 no.3
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• pp.17-27
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• 2016

In order to solve the problem of how to estimate the residential segregation, the Spatial Concentration Index(SCI) and Location quotient(LQ) are able to be one of alternative methods, and a comprehensive analysis of the residential segregation phenomenon in the seoul metropolitan area is the aim of the study. The results of SCI show that residential concentration areas in low-rent are some Gyeonggi-do's downtown(Bucheon-si, Suwon-si) as well as rural and urban-rural complex outskirts of the metropolitan area. The results of changing of SCI from 2011 to 2014, downward changes appeared thirteen districts and upward changes appeared fourteen districts. Especially downward change district was Sosa-gu, Bucheon-si and upward change district was Yeongtong-gu, Suwon-si. In conclusion, that high rent level groups are more concentration on specific area than low rent level groups. By decreasing residential concentration districts in low-rent level group, 'diversity' districts have been increasing in seoul metropolitan but the phenomenon of residential concentration in high and low level group have been being intensified. These results could be confirmed by quantitative through LQ. Methodologically LQ would strengthen the explanatory power of SCI, and ongoing research of SCI in conjunction with other quantitative methods will need.

• Journal of the Korean Society for Library and Information Science
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• v.50 no.3
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• pp.429-453
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• 2016

This study analyzes circulation patterns of books with checkout transaction count by 11 subject areas, 5 positions, and 5 divisions with a Use Factor developed by Bonn in an Academic Library. 20% of the loan books occupies more than half of circulation and these are regarded as core collection. It proposes a 'Loan books 20/50 rule' that 20% core collection accounts for 50% of its circulation. It analyzes the proportion of core collection from the aspect of each subject area with a use factor, monthly change trend and loan period. It also defines 'book usage' considering checkout frequency of each title and loan period. Circulation patterns of core collection are compared and analyzed in terms of both checkout frequency and book usage. Core collection occupies about more than half of both total checkout transactions and total book usages and they all show a Power Law distribution.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.46-54
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• 1998

In this paper, the erect of notch geometries on dynamic stress concentration was investigated by using the dynamic photoelasticity and the drop weight loading system Dynamic stress fields arisen by elastic wave through the loading system around various types of notch geometries were captured by using $10^6/sec$ frame rate Cranz-Shardin camera system with 12 photographic frames. We found that dynamic stress concentrations around the notch tip and comer were highly dependent on the change in notch geometries. The elders of dynamic stress singularity ware determined with respect to varying geometries of notches and we explained dynamic stress concentration in terms of the orders of dynamic stress singularity.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.48-55
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• 2009

In the glulam beam deflection it is necessary to check the reliability of theory formula, because of wood anisotropy and wood qualities (knot, slop of grain). In this experiment, when bending stress occurred on glulam, practice deflection of glulam measuring with AICON DPA-Pro 3D system were compared with prediction deflection calculated as substituting MOE through non-destructive testing and static MOE through bending test in differential equation of deflection curve. MOE using ultrasonic wave tester of laminae, MOE using natural frequencies of longitudinal vibrations ($E_{cu}$, $E_{cf}$), MOE using ultrasonic wave tester of glulam ($E_{gu}$) and MOE using natural frequencies of longitudinal vibrations ($E_{gf}$) were substituted in this experiment. When practice deflection measured by 3D system was compared with prediction deflection calculated with differential equation of deflection curve, within proportional limit the ratio of practice deflection and prediction deflection was similar as 1.12 and 1.14, respectively. Deflection using ultrasonic wave tester was 0.89 and 0.95, Deflection using natural frequencies of longitudinal vibrations was 1.07 and 1.10. The results showed that prediction deflection calculated by substituting using non-destructive MOE of glulam having anisotropy in differential equation of deflection curve was agreed well with practice deflection.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.479-492
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• 2004

When U-ribs of steel deck plates are connected at the field, overhead welding should be done with backing strips. Misalignments may occur and lead to eccentric moments as well as high stress concentrations at welded joints. In this study, stress analyses and fatigue tests were carried out. Stress analyses for U-ribs' welded joints with backing strips were performed with different misalignments, root shapes, root gaps, and backing strip sizes. From the stress analyses, the stress concentration factors increased with increasing misalignments and root gaps. With the fixed misalignments and root gaps, the stress concentration factors obtained in the case of the semi-circle root shape were lower than those in the case of the right-angle root shape. It was verified that backing strip sizes have little influence on stress concentration factors. The fatigue tests for U-ribs' welded joints with backing strips indicated that increased misalignments shorten fatigue life drastically and cracks usually initiate at the root of the base metal and are propagated to the weld bead surface. Based on the results of the stress analyses, root-shape control methods were developed to mitigate stress concentration by changing welding condition control, radius curvature, and flank angle.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.2
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• pp.73-85
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• 2016

Systematic and efficient forestry management is required because of the long-term low profitability of timber production and forest products. In this situation, non-timber forest products can be the solution to secure stable sources of income for workers in the forestry field. However, the existing studies for non-timber forest products focus on effective production and economic analysis and provide plans for increasing the income and improving the marketing system. Therefore, this research intends to analyze the spatial distribution as well as quantitative concentration of non-timber forest production. To achieve this goal, this study examined the regional concentration and dispersion of non-timber forest production in 2001, 2007, and 2014 using the coefficient of localization(CL) and location quotient(LQ) and investigated the change in spatial distribution using spatial statistics. The production of chestnuts generally showed a concentrated pattern in 2014 based on the outputs of the CL and LQ, but the result of spatial autocorrelation indicated a decrease in the spatial concentration. In addition, astringent persimmon showed more concentration from the output of CL than oak mushroom, but Moran's I suggests the opposite. Therefore, it is necessary to examine the spatial distribution to understand and improve the marketing system and intensify the production of forest products.

• Journal of the KSME
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• v.31 no.4
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• pp.356-363
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• 1991

선형 탄성 유한요소 응력해석과 평균응력 효과를 고려한 저주기 피로실험으로부터 결정된 피로 특성, 그리고 국부변형률 방법을 종합하여 외경에 흠이 존재하는 자긴가공된 두꺼운 압력 용기의 피로수명이 평가되었다. 직사각형의 매우 날카로운 흠에서의 응력집중계수는 타원형 홈에서의 응력집중계수의 약 두배의 값이 얻어졌으며, 고강도 압력용기강인 ASTM A723의 저주기 피 로거동에 대한 평균응력 영향은 Morrow 및 SWT 파라메타를 이용하여 충분히 고려되었다. 균열발생이 예상되는 위험한 부분인 홈의 뿌리부분에서의 국부적인 응력, 변형률이 계산되었으며 예측된 피로수명은 실험적으로 얻어진 수명과 비교했을 때 2에서 4배의 오차를 보이면서 일치 하는 결과를 얻었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.859-869
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• 2015

In this study, we analyze the problem of wedge cracks, which are geometrically unsymmetrical in transversely piezoelectric materials. A single concentrated antiplane mechanical load and inplane electrical load are applied at the point of the wedge surface, while one concentrated antiplane load is applied at the crack surface. The crack surfaces are considered as permeable thin slits, where both the normal component of electric displacement and the electric potential are assumed to be continuous across these slits. Using Mellin transform method, the problem is formulated and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress and the electric displacement are obtained for any crack length as well as inclined and wedge angles. Based on the results, the intensity factors are independent of the applied electric loads. The electric displacement intensity factor is always dependent on that of stress intensity factor, while the electric field intensity factor is zero. In addition, the energy release rate is computed. These solutions can be used as fundamental solutions which can be superposed to arbitrary electromechanical loadings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.167-175
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• 2014

If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis.

• Journal of the Korean association of regional geographers
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• v.14 no.4
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• pp.367-381
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• 2008

The purpose of this paper is to analyze the change in the distribution and hierarchical structure of commercial land use. Tools for analyzing the spatial structure are index of concentration, coefficient of localization and location quotient. This research is applied to Daegu, focusing on the period 1985-2003. During the 1985-2003 period, the growth rate of commercial land use volume amounted to 330%, compared with a population growth rate of 118%. The biggest component of commercial land use is the retail sector. As the lodging, medical, transportation-warehouse and entertainment sectors have the propensity for concentration and comprise the specialized commercial areas in the suburbs, the other sectors arc evenly distributed. Jung-gu has functioned as a downtown core in the hierarchical structure of commercial areas. So, in the structure of commercial land use, Daegu has continued to be a single nuclear structure. But, Dongdaegu Station influence area has evolved into the second order center since 2000. This is the sign of change in spatial structure from single-nuclear pattern to multi nuclear pattern.