• 한국산학기술학회논문지
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• 제12권3호
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• pp.1439-1443
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• 2011

본 연구에서는 지중 매설관 주변의 지하수 흐름을 이론적으로 규명해 보았다. 지하수 흐름에 있어서는 비압축, 비회전 흐름을 고려하였다. 지하수 흐름 해석시 복소 포텐셜을 이용하여 흐름을 정의하였는데 지중 매설관이 없는 경우의 균등흐름을 먼저 고려하였고 원 정리에 의해 지중 매설관의 영향을 기존의 균등흐름에 추가하였다. 복소 포텐셜의 선형성에 근거하여 두 개의 흐름을 중첩시킬 수 있으나 이때 특이점의 위치를 고려하여 적절한 복소 포텐셜을 적용함으로써 추가적인 특이점의 이미지를 삽입하지 않도록 하는 효율적인 해석이 필요하다. 최종적으로는 순환을 동반하는 지중 매설관 주변의 흐름을 복소 포텐셜 중첩을 통해 살펴보았고 그 경우 흐름에 의해 지중 매설관에 작용하는 작용력을 유도해 보았다.

• 한국대기환경학회지
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• 제14권3호
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• pp.219-228
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• 1998

In the present investigation, a numerical model developed for the prediction of the wind flow over complex terrain is validated by comparing with the field experiments. For the solution of the Reynolds - Averaged Clavier- stokes equations which are the governing equations of the microscale atmospheric flow, the model is constructed based on the finite-volume formulation and the SIMPLEC pressure-correction algorithm for the hydrodynamic computation. The boundary- fitted coordinate system is employed for the detailed depiction of topography. The boundary conditions and the modified turbulence constants suitable for an atmospheric boundary- layer are applied together with the k- s turbulence model. The full- scale experiments of Cooper's Ridge, Kettles Hill and Askervein Hill are chosen as the validation cases . Comparisons of the mean flow field between the field measurements and the predicted results show good agreement. In the simulation of the wind flow over Askervein Hill , the numerical model predicts the three dimensional flow separation in the downslope of the hill including the blockage effect due to neighboring hills . Such a flow behavior has not been simulated by the theoretical predictions. Therefore, the present model may offer the most accurate prediction of flow behavior in the leeside of the hill among the existing theoretical and numerical predictions.

• Tribology and Lubricants
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• 제32권1호
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• pp.9-17
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• 2016

Contact between solid surfaces is one of the most important factors that influence dynamic behavior in micro/nanoscale. Although numerous theories and experimental results on contact behavior have been proposed, a thorough investigation for nanomaterials is still not available owing to technical difficulties. Therefore, molecular dynamics simulation was performed to investigate the contact behavior of nanomaterials, and the application of conventional contact theories to nanoscale was assessed in this work. Particularly, the contact characteristics of cylindrical nanowires were examined via simulation and contact theories. For theoretical analysis, various contact models were utilized and work of adhesion, Hamaker constant and elastic modulus those are required for calculation of the models were obtained from both indentation simulation and tensile simulation. The contact area of the cylindrical nanowire was assessed directly through molecular dynamics simulation and compared with the results obtained from the theories. Determination of the contact area of the nanowires was carried out via simulation by counting each atom, which is within the equilibrium length. The results of the simulation and theoretical calculations were compared, and it was estimated that the discrepancy in the results calculated between the simulation and the theories was less than 10 except in the case of the smallest nanowires. As the result, it was revealed that contact models can be effectively utilized to assess the contact area of nanomaterials.

• Steel and Composite Structures
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• 제22권2호
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• 한국비블리아학회지
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• 제21권2호
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• pp.97-110
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• 2010

어린이 서비스의 전문성 확보를 위한 체계적이고 실질적인 교육을 위하여 어린이전문사서의 교육과정 모형을 개발하였다. 문헌연구 및 이론 분석, 설문조사, 문헌정보학과 교과과정 분석 결과에 기초한 어린이전문사서 교육과정 모형은 어린이사서, 어린이, 자료, 서비스, 운영 및 관리등 5개 영역으로 구분하였다. 교육과정은 '교양과정'과 '계속전문과정'으로 구분하여 관련 교과목을 개설하고, 교양과정은 총 90시간, 계속전문과정은 총 165시간으로 편성하였다. 교과목의 특성에 따라 일부 교과목은 이론수업과 실행 수업을 병행할 수 있도록 학점을 분리하여 구성하였다. 교육방법과 기간은 상시 개설되는 온라인 강좌와 특정 집중교육 기간 동안 이루어지는 오프라인 수업이 병행되는 통합형으로 제안되었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권11호
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• pp.547-554
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• 2006

The detent force of a permanent magnet linear motor(PMLM) consists of the end force and cogging force, and should be reduced for high precision purpose applications. The cogging force comes from the electromagnetic interaction between the permanent magnets and interior teeth(or the slots) of the stator, and of which the magnitude depends on the ratio of the numbers of the armature and permanent magnet poles as well as the geometrical shape of the permanent magnet and armature pole. In order to reduce the cogging force of a PMLM, this paper proposes a new configuration which has 9 permanent magnet poles and 10 armature winding slots. By theoretical investigation of the principle of cogging force generation and simulating using finite element method, the proposed PMLM configuration is proven to give much less cogging force than the conventional configuration which has 8 permanent magnet poles and 12 armature winding slots. A proper winding algorithm, modified (A, A, A) winding method, for the proposed configuration is also suggested when the proposed PMLM is operating as a 3 phase synchronous machine. A theoretical and numerical calculation shows that the proposed configuration makes slightly bigger back-emf and thrust force under same exciting current and total number of winding turns condition.

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.117-131
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• 2020

The adsorption of N-[(E)-Pyridin-2-ylmethylidene] aniline, a Schiff base, on to mild steel surface in 1M HCl and 0.5 M H₂SO₄ solutions and the consequent corrosion protection were studied employing weight loss method, electrochemical impedance spectroscopy and potentiodynamic polarization measurements. DFT calculations were performed to investigate its interaction with the metal surface at the atomic level to understand its inhibition mechanism. The adsorption process is well described by the Langmuir isotherm. The thermodynamic parameters indicated that the adsorption is spontaneous and the interaction of the inhibitor at the mild steel surface is mainly through physisorption. The R_a values obtained in AFM studies for the uninhibited and inhibited sample in HCl media respectively are 0.756 and 0.559 ㎛, and that in H₂SO₄ media are 0.411 and 0.406 ㎛. The lesser roughness values of the inhibited sample shows the adsorption of the molecules onto the mild surface. The inhibition efficiencies were found to improve with concentration of the inhibitor and the maximum efficiency was observed at 400ppm in all the investigation methods adopted. The inhibitor was found to exhibit a higher efficiency in HCl media (95.7%) than in H₂SO₄ (92.8%). The theoretical and experimental results are found to be in good agreement.

• 대한기계학회논문집
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• 제12권3호
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• pp.397-408
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• 1988

본 연구에서는 세가지 형상비의 연강판타원벌지 시험에 대하여 다이반경부분 의 형상과 수직이방성을 고려하여 해석고 이에 따른 실험과 비교검토하여 타원벌지시 험에서의 변형특성에 대해 논의하고자 한다. 또 불안정현상이 일어나는 압력을 예측 하여 실험에서 구한 파괴압력과 비교하여 타원벌지 시험에서의 파괴특성을 고찰하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권5호
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• pp.2061-2083
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• 2020

Social commerce, integration of social media and e-commerce, provides potential opportunities for consumers to talk about their ideas and exchange product-related information on online shopping platforms. Given the substantial prospects related to business opportunities and consumers' perceptions, this study explores the factors driving fulfillment of the psychological contract in social commerce platforms. This research proposes, examines, and proves a theoretical model for the post-purchase behavior of the consumers, through an empirical investigation of online questionnaire-based data, gathered from 367 consumers in a cross-sectional setting. Results show that the fulfillment of psychological contract, consumer loyalty, and affective commitment fully mediate the impact of consumer trust on platform and repurchase intention. The level of commitment toward the consumer by the platform is strongly related to the degree of consumer trust, which is reciprocated through re-purchase intentions. This study offers essential theoretical implications with regards to the social exchange theory, attribution theory, and an moderating effect of the platform empathy on consumers' trust-psychological contract fulfillment relationship. Likewise, this research has significant implications for practitioners and managers.

• 산업경영시스템학회지
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• 제2권2호
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• pp.93-103
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• 1979

As principles of our country's Business Enterprises Account are being developed, Customs of Business Enterprises Account are in the state of change and then Principles of that are in revision. According to systematizing contents of such a principle of Business Enterprises Account, having made an analysis and Investigation from versatile situation, I can deprive of the following conclusions from above facts. 1. The prelude of a general principle involves compulosory character like a forced law rather than a theoretical teaching of original character. 2. Because of making much of supply of account information, To make mistakes, emphasis on function of an information, on the other side, being apt to disregard control function of original account. 3. There is no such a mutual relation as theoretical systematic form among general rule, a profit-and-loss account, balance sheet and drawing principle. These rules which don't form gradual structure are prescribed respectively according to business like necessity. 4. An overall contents of account principle are regarded as principle near financial account rather than the Pivot of administration account. In the future, The whole academic world of account and business practice should become the idealistic account principle with lots of study and effort.