• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_3호
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• pp.97-106
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• 2001

To improve the water quality, particularly for sea bathers, the behaviour of wastewater from sewage outfalls in water adjacent to Swansea, UK, was studied using a mathematical model. The water quality in the sewage receiving basin was determined using factors like the outfall diffuser location(distance from land boundary), sewage treatment scheme, discharge time, and bacteria decay rate, etc. With respect to these factors, an optimal strategy for sewage discharge was then investigated to minimize bacteria levels along the bathing beaches. As water quality criteria, predicted faecal coliform levels were monitored along the coast adjacent to the outfall locations. The resultant values were compared with EC Mandatory(<2000, 95 % of 20 samples) and Guideline Standards(< 100, 80 % of 20 samples). For the advective-diffusion equation, the non linear advective terms were represented using the ULTIMATE algorithm and the third-order accurate QUICKEST scheme to avoid numerical diffusion. Details of the simulation results are then presented as an optimal policy for sewage discharge in the region.

• 대한전기학회논문지
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• 제32권4호
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• pp.136-144
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• 1983

In this paper, a new scheme of implicit MRAC is presented for single input single output discrete system. The MRAC can be applied to the nonminimum phase system, too. They have simple structure because the parameters of the controller are estimated directly by changing the plant output equation properly. In this scheme, the observation process is well seperated from the adaptation process, so the adaptation algorithm is derived from the exponentially weighted least square method which has fast convergence characteristics and can deal with the time varying plant. The consistency of the estimated parameter is proved. And it is also proved the whole system has the stabilizing property. The effectiveness of the algorithm and the structure is illustrated by the computer simulation of the model reference adaptive control for a third order plant. It is proposed how to select the selectable parameters in the adaptive control system from the simulation results.

• East Asian Economic Review
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• 제23권3호
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• pp.311-329
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• 2019

Since China's opening to international trade, the rapid growth of the country's export sector has been coupled by an intensification of migratory outflows of ethnic Chinese. The literature has already stressed the beneficial role of migration in enhancing bilateral trade. The present paper applies a gravity model in order to capture the impact of migration on Chinese exports for a relatively long period of time (1995-2017) where significant developments take place. We estimated four regressions, each of them confirming the positive network effects of migration for boosting export growth. Apart from the main finding, it appears that the role of institutional and geographical proximity can prove to be complementary for trade enhancement. The results finally suggest mixed effects due to the countries' import openness, indicating that China's free trade agreements acts as a substitute for smoothing trade competition from third countries.

• Steel and Composite Structures
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• 제32권5호
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• pp.687-699
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• 2019

In this paper, free and force vibration behaviors of graphene-reinforced composite functionally graded (GRC-FG) cylindrical shells in thermal environments are investigated based on Reddy's third-order shear deformation theory (HSDT). The GRC-FG cylindrical shells are composed of piece-wise pattern graphene-reinforced layers which have different volume fraction. Based on the extended Halpin-Tsai micromechanical model, the effective material properties of the resulting nanocomposites are evaluated. Using the Hamilton's principle and the assumed mode method, the motion equation of the GRC-FG cylindrical shells is formulated. Using the time- and frequency-domain methods, free and force vibration properties of the GRC-FG cylindrical shell are analyzed. Numerical cases are provided to study the effects of distribution of graphene, shell radius-to-thickness ratio and temperature changes on the free and force vibration responses of GRC-FG cylindrical shells.

• International Journal of Internet, Broadcasting and Communication
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• 제14권3호
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• pp.213-221
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• 2022

The purpose of this study is to investigate the structural relationship between media engagement, viewing immersion, viewing satisfaction, and loyalty of e-sports viewers. In order to achieve the purpose of this study, a survey was conducted on 300 college students with experience in watching e-sports in Seoul, Gyeonggi-do, and Chungnam. Data processing was done with SPSS 26 for frequency analysis, Cronbach's α analysis. Also, AMOS 13 was used for confirmatory factor analysis and structural equation model analysis. We have the following results. first, among the sub-factors of media engagement, functional engagement and communal engagement had a significant effect on viewing commitment. Second, among the sub-factors of media engagement, emotional engagement had a significant effect on viewing satisfaction. Third, it was found that viewing commitment and viewing satisfaction had a significant effect on loyalty. From the results of this study, it can be seen that the media engagement of e-sports viewers affects loyalty through viewing commitment and viewing satisfaction.

• 한국정보시스템학회지:정보시스템연구
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• 제32권4호
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• pp.51-67
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• 2023

Purpose While research on ESG management in airlines is ongoing, research on airports, especially regional ones, remains insufficient. This study's point of departure is the inquiry into how the local airport industry is addressing global environmental shifts and engaging in ESG management activities. Design/methodology/approach Based on previous studies, the relationship between ESG(Environmental, Social, Governance) management, safety management, reputation, and management performance was analyzed. We analyzed 578 questionnaires through structural equation modeling using AMOS 21.0 to test our hypotheses. Findings First, environmental, social, governance, and safety management have a positive effect on both reputation and business performance. Second, reputation has affected business performance. Third, reputation was affected in the order of governance management, safety management, environmental management, and social management.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5542-5550
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• 2012

Eringen의 비국소 탄성이론을 이용한 3차 전단변형이론을 정식화 하였고 비국소 탄성이론이 적용된 평형방정식을 유도하였다. 비국소 탄성 이론은 미소 규모 효과를 고려할 수 있고 3차원 전단변형이론은 나노 판의 두께방향으로의 전단변형률과 전단응력의 곡선변화 효과를 고려할 수 있다. 모든 변이 단순지지된 나노-스케일 판의 지배방정식을 풀기 위해 Navier 방법을 사용하였다. 비국소 변수의 효과를 나타내기 위한 나노-스케일 판의 해석적 좌굴하중을 제시하였다. 국소 탄성이론과의 관계를 수치해석 결과를 통하여 고찰하였다. 또한 (i) 나노-스케일 판의 크기, (ii) 비국소 계수, (iii) 형상비 그리고 (iv) 모드 수 등이 나노-스케일 판의 무차원 좌굴하중에 미치는 효과에 대하여 관찰하였다. 본 연구의 결과를 검증하기 위해 참고문헌의 결과들과 비교 분석하였으며 해석결과는 참고문헌의 결과들과 잘 일치함을 알 수 있었다. 비국소 이론에 의한 나노-스케일 판의 좌굴해석에 관한 연구는 향후 관련연구에 비교자료로 활용될 수 있을 것이다.

• 한국초등수학교육학회지
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• 제21권3호
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• pp.531-546
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• 2017

본 연구에서는 계산 순서를 지도하는데 유용한 교수법적 내용 지식을 제공하기 위해 사칙계산 사이의 우선권은 어떠한 근거로 결정되었는지 살펴보고, 계산 순서를 바라보는 입장에 관해 논의하였다. 이러한 논의 결과를 바탕으로 다음 다섯 가지 제언을 결론으로 제시한다. 첫째, 교사들에게 덧셈과 뺄셈의 혼합계산 및 곱셈과 나눗셈의 혼합계산의 경우, 각각 뺄셈과 나눗셈부터 계산해도 동일한 계산 결과를 구할 수 있다는 것을 확인하는 기회를 제공할 필요가 있다. 둘째, 교사들에게 식의 왼쪽부터 차례대로 계산하는 규칙이 관습으로 자리 잡은 이유에 관해 논의할 수 있는 기회를 제공할 필요가 있다. 셋째, 교사들에게 덧셈과 곱셈의 혼합계산에서 곱셈이 덧셈보다 우선한다는 규칙 설정의 동인을 설명해 보는 기회를 제공할 필요가 있다. 넷째, 교사들에게 괄호가 있는 식에서 하나의 수량이라는 괄호의 의미를 강조할 필요가 있다. 다섯째, 교사용 지도서에서 계산 순서의 입장을 기술할 때는 계산 순서의 관습적, 개념적 입장을 모두 기술하여 교사들의 계산 순서에 대한 이해를 심화시킬 필요가 있다.

• 대한화학회지
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• 제33권3호
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• pp.309-314
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• 1989

산 용액내에서 cis-$[Co(en)_2(N_3)_2]^+$와 Fe(II)간의 산화-환원 반응속도를 UV/vis-분광광도계로 측정하였다. 여기서 촉매 $H^+$가 관여한 반응속도상수와 각 반응물의 반응차수 그리고 활성화파라메타를 구하여 이들 자료를 바탕으로 타당한 반응메카니즘을 제안하였다. 본 연구의 실험결과를 보면, Co(III)와 Fe(II) 그리고 $H^+$에 대해서 각각 1차로 총괄반응이 3차 반응이다. 이때 반응속도상수 $K_H^+$는 $3.27{\times}10^{-2}l^2{\cdot}mol^{-2}{\cdot}sec^{-1}$이였다. 그리고 활성화에너지 $E_a$는 14.8Kcal/mol, 활성화엔탈피 ${\Delta}H^{\neq}$는 14.2Kcal/mol, 활성화엔트로피 ${\Delta}S^{\neq}$는 -16.7e.u.였다. 이러한 실험적 사실을 바탕으로, 본 반응계에서 $H^+$가 촉매로 작용하여 내부권(inner-sphere) 메카니즘으로 산화-환원반응이 진행되는 타당한 반응메카니즘을 제안하였다.

• International journal of advanced smart convergence
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• 제10권4호
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• pp.158-164
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• 2021

The purpose of this study is to analyze the structural relationship between customer's pleasure, customer satisfaction, switching cost, and relationship commitment using the fitness center and provide implications. Specifically, this study aims to investigate the effect of the degree of customer's awareness of pleasure on the relationship commitment through the medium of customer satisfaction and switching cost. For this purpose, the structural equation model was constructed based on the previous studies, and the exogenous variables were pleasure, and the endogenous variables were customer satisfaction, switching costs and relationship commitment. The subjects of this study were customers who used fitness centers in the metropolitan area. The sampling method for the sample survey was a total of 277 people using convenience sampling. 257 copies were used as final data except for 20 samples that were not appropriate for the study. The statistical program for data analysis was IBM SPSS Ver. 26.0 and Amos 21.0. The specific data processing method is as follows: First, frequency analysis was conducted to understand the general characteristics of the subjects. In order to verify the validity and reliability of the research tools, confirmatory factor analysis and reliability analysis were conducted. In order to understand the theoretical relationship between each variable, structural equation model was conducted. The results of data processing on the research model are as follows: First, the pleasure of the fitness center customers had a positive effect on customer satisfaction. Second, customer satisfaction had a positive effect on the switching costs. Third, customer satisfaction had a positive effect on the customer commitment. Fourth, switching costs had a positive effect on customer commitment.