• 한국산림과학회지
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• 제21권1호
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• pp.39-45
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• 1974

지위지수추정시 발생되는 오차를 감소시키기 위하여 수고생장과정에 적합한 실험식과 기타 정보를 얻고자 이 연구를 착수한 것이다. 11개 실험식으로 물오리나무, 일본잎갈나무, 잎갈나무, 잣나무, 젓나무, 리기다소나무, 상수리나무와 갈참나무의 수고생장 추정식을 계산하였다. 계산결과에 의하면 수종간에는 적합실험식의 종류가 서로 다르며 지위지수는 임령에 따라 항상 일정한 것이 아니고 변동하는 경우가 있으므로 지위지수추정시 수간석해 또는 다변형지위지수 곡선을 이용함이 합리적인 것으로 생각된다.

• 생태와환경
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• 제43권4호
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• pp.503-512
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• 2010

This study was conducted to evaluate fish fauna, species composition, and various guilds against stream orders along with analysis of fish community structure and diversity in Geum River watershed from 2005 to 2007. The total number of fish collected was 4,216 representing 12 families with 56 species. Zacco platypus was the most abundant fish species with 26% in relative abundance (RA). Korean endemic species were 24 species including Zacco koreanus, Microphysogobio yaluensis, Gobiobotia nakdongensis, and Iksookimia koreensis, etc. We also collected endangered fish species such as G. nakdongensis, Liobagrus obesus, and Pseudopungtungia nigra, etc., and their new distribution sites were found in the survey, providing some sites of the fish conservation and protection. Fish tolerance and trophic guilds analysis showed that the proportion of sensitive species, intermediate species, and tolerant species were 33.4%, 29.3%, and 37.3%, respectively and omnivores and insectivores were 48.1 % and 38.4%, respectively. Analysis of site-base study indicated that tolerant species and omnivore species were high in some polluted tributary streams (i.e., Gap and Miho stream) and sensitive and insectivore species were low. In the functional relations, expressed as simple linear regression equations, of stream order on fish metric attributes, showed that the number of species and the number of individuals increased as the stream order increases. This phenomenon was explained by greater availability of stable water volume, rich food, and higher physical habitat capacity. Such guild compositions and stream order characteristics of the river influenced the community structures, based on species diversity, dominance and evenness index in the study. This study may be used as important data in the future for comparisons of fish fauna and compositions before and after two weir (dam) constructions in the middle of Geum River by the government.

• 유기물자원화
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• 제22권2호
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• pp.17-26
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• 2014

본 연구에서는 벤토나이트를 이용하여 수용액상에서 혼합 중금속의 흡착 특성을 평가하였다. 벤토나이트는 SEM과 FT-IR에 의해 물리 화학적 성상을 분석하였고, 중금속 흡착 특성은 Freundlich 및 Langmuir 방정식을 이용하여 해석하였다. 평형흡착 실험결과는 Langmuir 모델에 잘 부합되었으며, $Pb^{2+}$ > $Cu^{2+}$ > $Cd^{2+}$ > $$Zn^{2+}{\sim_=}Ni^{2+}$$순으로 평형 흡착량이 높았다. 용액의 pH가 6에서 10으로 증가함에 따라 흡착량은 증가하는 경향을 나타내었다. SEM과 FT-IR에 의한 벤토나이트의 표면 관찰결과에서 주 관능기는 Si-O 및 Si-O-Al 로 나타났다. 이러한 결과로부터 중금속 흡착 메카니즘은 표면흡착과 이온교환뿐만 아니라 표면 침전이다. 본 연구 결과를 통해 벤토나이트는 수용액 내 중금속을 효율적으로 제거할 수 있는 흡착제로 판단된다.

• 지구물리와물리탐사
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• 제10권2호
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• pp.147-153
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• 2007

CG (conjugate gradient) 법은 선형 연립방정식을 반복적으로 푸는 가장 효율적인 해법 중 하나이고, 또한 비선형 최소자승문제에도 적용할 수 있다. 자기지전류(MT) 역산 문제를 풀 때에는 최소자승문제의 목적함수 자체의 최소화에 직접 CG 법을 적용하거나, Gauss-Newton 법에 기초한 반복역산의 각 반복단계에서 모형의 변화량 계산에 CG 법을 이용할 수 있다. CG 법을 적용할 경우, 임의의 벡터에 대한 감도행렬의 영향 및 그 전치행렬의 전치행렬의 영향을 감도행렬을 직접 구하지 않고 계산할 수 있다는 장점이 있기 때문에 감도행렬의 계산 규모가 방대한 3차원 역산 문제에서 계산시간을 월등히 줄일 수 있다.

• 한국전문물리치료학회지
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• 제20권4호
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• pp.55-64
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• 2013

The first purpose was to identify the plantar pressure distributions (peak pressure, pressure integral time, and contact area) during level walking, and stair ascent and descent in asymptomatic flexible flatfoot (AFF). The second purpose was to investigate whether peak pressure data during level walking could be used to predict peak pressure during stair walking by identifying correlations between the peak pressures of level walking and stair walking. Twenty young adult subjects (8 males and 12 females, age $21.0{\pm}1.7$ years) with AFF were recruited. A distance greater than 10 mm in a navicular drop test was defined as flexible flatfoot. Each subject performed at least 10 steps during level walking, and stair ascent and descent. The plantar pressure distribution was measured in nine foot regions using a pressure measurement system. A two-way repeated analysis of variance was conducted to examine the differences in the three dependent variables with two within-subject factors (activity type and foot region). Linear regression analysis was conducted to predict peak pressure during stair walking using the peak pressure in the metatarsal regions during level walking. Significant interaction effects were observed between activity type and foot region for peak pressure (F=9.508, p<.001), pressure time integral (F=5.912, p=.003), and contact area (F=15.510, p<.001). The regression equations predicting peak pressure during stair walking accounted for variance in the range of 25.7% and 65.8%. The findings indicate that plantar pressures in AFF were influenced by both activity type and foot region. Furthermore the findings suggest that peak pressure data during level walking could be used to predict the peak pressure data during stair walking. These data collected for AFF can be useful for evaluating gait patterns and for predicting pressure data of flexible flatfoot subjects who have difficulty performing activities such as stair walking. Further studies should investigate plantar pressure distribution during various functional activities in symptomatic flexible flatfoot, and consider other predictors for regression analysis.

• Steel and Composite Structures
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• 제25권1호
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• pp.105-116
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• 2017

This paper presents the dynamic stability study of laminated composite plates with different force combinations and aspect ratios. Optimum non-diverging stacking is obtained for certain loading combination and aspect ratio. In addition, the stability force is maximized for a definite operating frequency. A dynamic version of the principle of virtual work for laminated composites is used to obtain force-frequency relation. Since dynamic stiffness governs the divergence or flutter, an efficient optimization method is necessary for the response functional and the relevant constraints. In this way, a model based on the ant colony optimization (ACO) algorithm is proposed to search for the proper stacking. The ACO algorithm is used since it treats with large number of dynamic stability parameters. Governing equations are formulated using classic laminate theory (CLT) and von-Karman plate technique. Load-frequency relations are explicitly obtained for fundamental and secondary flutter modes of simply supported composite plate with arbitrary aspect ratio, stacking and boundary load, which are used in optimization process. Obtained results are compared with the finite element method results for validity and accuracy convince. Results revealed that the optimum stacking with stable dynamic response and maximum critical load is in angle-ply mode with almost near-unidirectional fiber orientations for fundamental flutter mode. In addition, short plates behave better than long plates in combined axial-shear load case regarding stable oscillation. The interaction of uniaxial and shear forces intensifies the instability in long plates than short ones which needs low-angle layup orientations to provide required dynamic stiffness. However, a combination of angle-ply and cross-ply stacking with a near-square aspect ratio is appropriate for the composite plate regarding secondary flutter mode.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.457-467
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• 2020

세계적으로 환경문제에 관한 우려가 급증하여, 세계 각국이 온실가스 연비 규제를 강화하고 있다. 연비향상을 위해 첨단 운전자 지원 시스템을 이용한 연구를 통하여, 운전자의 편의를 위해 다양한 첨단 운전자 지원 시스템을 개발하고 있다. 그중 ACC, LKAS, AEB 등의 시스템에 대한 연구가 활발하다. ACC의 목적은 차량의 종 방향 속도와 거리를 제어하고 운전자의 부하를 최소화하여 사고 예방과 방지에 유용한 시스템으로 평가되고 있다. 이러한 관점에서 본 논문은 선행연구에서 제안한 국내도로 환경을 고려한 시나리오와 거리에 대한 함수로 안전성을 평가할 수 있는 수학적 방법을 활용한다. 또한, 제안한 시나리오를 기반으로 시뮬레이션과 실도로 실차시험을 진행한 뒤, 이론수식을 활용한 이론 계산값, 시뮬레이션과 실도로 실차시험의 상대거리의 비교분석을 통하여 ACC의 기능적인 안전성을 검증하고자 한다. 이러한 방법을 통하여 많은 회사들이 ACC의 개발 단계에서 시나리오, 수식, 시뮬레이션을 활용하여 안전성 평가방법으로 활용할 수 있을 것으로 예상된다.

• 대한조선학회지
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• 제11권1호
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• pp.27-34
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• 1974

This study is aimed at a validation of the vigilance simulation model which was proposed earlier (2). The model estimates a perceived danger value, an alertness level and the probability of detection at a given elapsed time of vigilance. Twenty-nine male and seven female subjects were given a simple task. They were asked to detect a number(four numbers out of six digits in the telephone directory which have the probability of occurrence in the range of 0.0010-0.0018) in six different experimental conditions, for periods of two to three hours. Analysis of the experiments showed that although the mean detection rate varied slightly in two hours, the within-subject variance and the number of cyclic performance fluctuations increased significantly. A primal factor that affects the performance seems to be the frequency of target occurrence. By curve fitting, the relation between the probability of detection and the percentages of danger event occurrence was derived; $y=0.50(1-{\varepsilon}^{-50x^2})+0.39$. Assuming the equation represents the normal detection rate(100% performance), the Relative Vigilance Performance Rating was calculated. This rating method could be a useful criterion in selecting and training of the vigilance personnel. The results show that the simulation model is a good estimator of human a performance when the probability of danger occurrence is greater than 0.0015; it gives a good reference for improving the vigilance system. Suggestions are made that (1) the validity of proposed functional equations over the extended range of danger probability be studied, (2) an analysis of the cyclic fluctuations of the alertness level be accomplished, and (3) the cost functions of detection reliability be included in any future model.

• The Korean Journal of Physiology and Pharmacology
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• 제23권1호
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• pp.63-70
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• 2019

We aimed to propose a novel computational approach to predict the electromechanical performance of pre- and post-mitral valve cerclage annuloplasty (MVCA). Furthermore, we tested a virtual estimation method to optimize the left ventricular basement tightening scheme using a pre-MVCA computer model. The present model combines the three-dimensional (3D) electromechanics of the ventricles with the vascular hemodynamics implemented in a lumped parameter model. 3D models of pre- and post-MVCA were reconstructed from the computed tomography (CT) images of two patients and simulated by solving the electromechanical-governing equations with the finite element method. Computed results indicate that reduction of the dilated heart chambers volume (reverse remodeling) appears to be dependent on ventricular stress distribution. Reduced ventricular stresses in the basement after MVCA treatment were observed in the patients who showed reverse remodeling of heart during follow up over 6 months. In the case who failed to show reverse remodeling after MVCA, more virtual tightening of the ventricular basement diameter than the actual model can induce stress unloading, aiding in heart recovery. The simulation result that virtual tightening of the ventricular basement resulted in a marked increase of myocardial stress unloading provides in silico evidence for a functional impact of MVCA treatment on cardiac mechanics and post-operative heart recovery. This technique contributes to establishing a pre-operative virtual rehearsal procedure before MVCA treatment by using patient-specific cardiac electromechanical modeling of pre-MVCA.

• 한국산업정보학회논문지
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• 제27권5호
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• pp.99-117
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• 2022

본 연구는 서비스기업 중 하나인 은행 구성원을 대상으로 은행의 고객경험관리역량이 조직구성원의 직무만족 및 고객지향성에 어떤 영향을 미치는지 확인하고자 한다. 이를 위해 고객경험관리역량, 직무만족, 고객지향성에 대한 이론을 설명하고 이들 간의 관계를 이론 및 실증적으로 검증하였다. 본 연구를 위하여 은행에서 근무하는 접점직원 321명을 대상으로 SPSS23.0, AMOS 23을 이용해 구조방정식 분석을 실시하였다. 본 연구의 분석결과를 살펴보면 은행의 고객경험관리역량의 요소 중 구성원교육, 임파워먼트, 구성원평가, 교차검정은 직무만족 및 고객지향성에 긍정적 영향이 있는 것으로 나타났다. 이에 반해 채널통합은 직무만족과 고객지향성 모두 영향을 미치지 못했으며, 성과관리는 직무만족을 매개로하여 고객지향성에 영향을 미쳤다. 이러한 결과는 조직단위에서 고객경험관리역량을 확인할 수 있는 시사점을 제시하지만, 서비스기업이 은행으로 한정되었다는 한계도 존재한다.