낙동강 하구에서 담수 유입에 따른 연안 클로로필-a 증가 : 낙동강의 육상-해양 coupling 패턴 분석

김수현,안순모 한국해양학회 2021 바다 Vol.26 No.2

Since terrestrial input plays a major role in coastal primary production, an understanding of land-ocean coupling (LOC) is key to understand coastal ecological changes. In this study, the LOC has been classified into three stages (i.e., the baseflow, plume event and residual flow). In order to characterize its pattern in Nakdong River estuary, multi-platform data were obtained from remote sensing (geostationary ocean color image (GOCI)), in-situ measurement (marine environment information system (MEIS)), on-site measurement (discharge data and meteorological data). The MEIS data were grouped into three stages of LOC using principal component analysis (PCA), and the LOC (2013 ~ 2018) was examined at each stage using multi-platform data. In the Nakdong River estuary, the maximum value of chlorophyll-a (chl-a) was unexpectedly appeared during the plume event. It is assumed that there was no significant increase in turbidity, expected during the typical plume event, together with the weak flushing effect, caused the enhanced phytoplankton growth. Compared with other estuaries, LOC is common in estuaries affected by freshwater inflow, but LOC has different pattern depending on the size of the plume. While estuaries that form small plumes of about 10 km (low freshwater discharge and weak flushing effect) observed high chl-a in the plume event because the phytoplankton can response to the increased nutrient more rapidly. estuaries that form large plumes of more than 100 km est (high freshwater discharge and strong flushing effect) follow the typical LOC pattern conceptualized in this study (high chl-a in the residual flow) 담수를 통해 유입되는 육상 기원 물질은 연안 일차 생산을 제어하는 주요 요소이므로 육상-해양 coupling을 파악하는 것은 연안 생태변화를 이해하는데 중요하다. 본 논문에서는 육상-해양 coupling 양상을 시간에 따라 세 단계(Base flow, Plume event, Residual flow) 로 구분하여 개념화하였고, 낙동강 하구에서 각 양상의 출현을 확인하기위해 다양한 플랫폼에서 측정된 자료를 사용하여 분석하였다. 사용된 자료는 원격 탐사 측정 자료(Geostationary Ocean Color Image; GOCI), 현장 실측 자료(Marine Environment Information System; MEIS), 연속 측정 자료(유량 자료, 기상 자료)로 구분될 수 있다. 주성분분석을 통해 MEIS 자료를 육상-해양 coupling의 세 단계로 구분하였고, 이 구분을 2013-2018년 동안의 여타 자료에 적용하여 단기간 육상-해양 coupling 양상을 살펴보았다. 낙동강 하구에서는 예상과는 달리 Plume event때 Chlorophyll-a (Chl-a) 최대값이 나타났다. 이는 담수 증가에도 탁도 증가는 크지 않았고, 플러싱효과도 약해 식물플랑크톤이 증가 할 수 있는 여건이 조성되었기 때문으로 분석되었다. 육상-해양 coupling을 기반으로 여러 하구들과 비교해보았을 때 육상-해양 coupling은 담수 유입에 영향을 받는 하구에서 흔한 현상이나 하구에서 형성되는 플룸 크기에 따라 육상-해양 coupling이 다르게 나타났다. 낙동강 하구처럼 작은 플룸(~10 km 규모) 이 형성되는 하구에서는 식물플랑크톤의 즉각적인 반응으로 인해 Plume event 단계에 Chl-a 최댓값이 나타나는 반면, ~100 km 이상의 큰 플룸이 형성되는 하구(담수 배출이 크고, 플러싱이 강한 곳)에서는 본 연구에서 개념화한 육상-해양 coupling 양상(Residual flow 때 Chl-a 최대)을 따르는 것으로 나타났다.

커플링 정도와 상세에 따른 병렬 전단벽의 내진거동 비교

윤현도 ( Yun Hyun-do ),박완신 ( Park Wan-shin ),이주화 ( Lee Joo-hwa ),박희연 ( Park Hee-yeon ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.7 No.2

In high multistory, reinforced concrete buildings, coupled shear walls(CSWs) can provide an efficient structural system to resist horizontal forces due to wind and seismic effects. Behavior of these structures depend on degree of coupling and details of coupling beam. This paper composed of two subjects. First subject is a verification of proposed statistical regression formula for evaluation of the degree of coupling and determination of fundamental periods of CSWS by Chaallal et al. Second subject is a comparison of elastic behavior and nonlinear seismic behavior of fully coupled shear wall and partially coupled shear wall for Details and Degree of coupling. This paper used IDARC-2D and Midas Gen 4.3.1 for the purpose of achievement these subjects. Analysis results shows that statistical regression formula by Chaallal revise a little. Elastic and nonlinear seismic analytical result shows that steel coupling beam and diagonally reinforced concrete coupling beam have good behavior. Also, fully coupled shear wall have good behavior than partially coupled shear wall.

Improvement of the Beam-Wave Interaction Eciency Based on the Coupling-Slot Configuration in an Extended Interaction Oscillator

Sairong Zhu,Yong Yin,Liangjie Bi,Zhiwei Chang,Che Xu,Fanbo Zeng,Ruibin Peng,Wen Zhou,Bin Wang,Hailong Li,Lin Meng 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.9

A method aimed at improving the beam-wave interaction eciency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The disper- sion characteristics, coupling coecient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam- wave interaction eciency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction eciency so that the EIOs are able to work in the 2 mode. The in uence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction eciency. Its maximum output power is 2.8 kW and the eciency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot con- gurations enables the extended interaction oscillator to meet the different engineering requirements better.

소비자의 거래커플링 지각과 소비행동의 적극성이 선구매 서비스의 획득가치와 만족에 미치는 영향에 관한 탐색적 연구

박소진 ( Park So Jin ),최낙환 ( Choe Nag Hwan ) 한국소비자학회 2004 소비자학연구 Vol.15 No.1

In the study of transaction coupling and consumer behavior it is argued that the cognition of consumer`s transaction coupling would affect the consumer`s decision of whether they will consume the products previously purchased. This research finds that the cognition of consumers` transaction coupling affect the activeness of consumption behavior and satisfaction. We classify the transaction coupling which is a mental accounting process, into `coupling before consumption` and `coupling during consumption`. Also we divide the activeness of consumption behavior into `the activeness of consumption-supporting behavior` and `the activeness of consumption-process behavior`. To be more specific, this research provides a multi-relationship model of coupling before consumption and coupling during consumption, and further models the activeness of consumption-supporting behavior, the activeness of consumption-process behavior, acquisition utility, and satisfaction. In order to verify the model and hypotheses, we conducted a survey. The respondents were consumers who had been purchased traveling service recently in C area of South Korea. We analyzed our research model utilizing LISLEL 8.30 and SPSS 10.0. The research findings indicate that in case of advance purchase of service product, consumer`s coupling-before-consumption positively affects the activeness of consumption-supporting behavior, and the activeness of consumption-supporting behavior is positively significant to the activeness of consumption-process behavior. Finally, it is verified that the activeness of consumption-process behavior affects consumer satisfaction directly or indirectly through acquisition utility.

Dynamic Wind Response of Twin Tall Buildings Linked by a Skybridge

Lim Juntack 한국풍공학회 2019 한국풍공학회지 Vol.23 No.3

스카이브릿지로 연결된 쌍둥이 초고층건물은 두 가지 종류의 연동성-스카이브릿지로 인해 두 건물의 거동 동기화를 유발하는 구조적 연동성과 작용하는 풍하중의 높은 상관성으로 인한 공기역학적 연동성-이 나타난다. 단일 건물에 널리 적용되는 전통적인 풍력실험 방법으로는 이런 연동성과 영향들을 완벽히 파악할 수 없는 실정이다. 그런 이유로 보다 발전된 동적 풍응답 해석법이 요구된다. 이 논문은 스카이브릿지로 연결된 쌍둥이 건물에서 발생하는 구조적 및 공기역학적인 연동성을 다룰 수 있는 듀얼 풍력실험 방법을 자세히 다루었다. 제안된 방법을 적용하여 건물의 풍가속도에 대한 구조적 및 공기역학적 연동성의 영향을 평가하였다. 건물의 풍응답 산정에 스펙트럼 적분법과 백색 소음 근사법을 적용하였다. 실험 및 결과로 볼 때 동적 풍응답에 상당한 영향이 있음을 확인할 수 있었다. 여러 개의 풍력 측정센서를 활용한 풍력실험 기술은 구조적으로 연결된 초고층건물에 대한 풍동실험에 유용하게 사용될 것으로 판단된다. Twin tall buildings linked a skybridge involve two types of coupling: the structural coupling, developed by a skybridge, synchronizing the motions of vibration of the two building and the aerodynamic coupling resulting from high cross-correlations of the components of wind loading. From the wind engineering viewpoint, an understanding of these couplings and their impacts on the wind-induced response of the buildings can not be fully accounted for when using the traditional high-frequency force balance (HFFB) approach tailored for single tall buildings, and thus this requires utilization of advanced dynamic wind response analysis. This paper addresses the dual- HFFB approach accounting for correlated wind loading and structurally coupled response of twin buildings with a skybridge. The proposed method is subsequently used to investigate the effects of aerodynamic and structural couplings on the rooftop accelerations of the buildings. Spectral integration and white-noise approximation approaches are employed in calculations of the building responses. The presented results show significant effects of both the aerodynamic and structural couplings. The multi-HFFB technique would be useful for wind tunnel study of structurally connected tall buildings.

승용차용 Trailer Coupling 장치 유럽 내구평가 기술 개발

김대성(Daesung Kim),김기훈(Gihoon Kim),강우종(Woojong Kang) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Trailer coupling devices for passenger car or SUV were used frequently in Europe and America to carry loads though they were rarely used in this country. The trailer coupling must be reliable because severe accident can occur when the trailer coupling fails. In this study, the durability evaluation technique for trailer coupling was developed to guarantee the reliability of vehicles exporting to European countries. We participated CARLOS (Car Loading Standard) committee so as to establish fundamental technique for trailer coupling. The load cell to measure forces on trailer coupling was developed and the forces was measured on service condition. The test condition was defined from the measurement. The durability of trailer coupling devices was evaluated with test and analysis under various conditions.

스핀-궤도 결합과 훈트 결합의 경쟁: t52g 전자구조를 중심으로

고아라 한국물리학회 2021 새물리 Vol.71 No.8

The effective angular momentum jeff efficiently describes the t2g orbitals in the presence of spin-orbit coupling. On the other hand, the d-orbital is spatially localized, and the local electrons have strong mutual two-body interactions, which play an important role in the metal-insulator transitions in transition-metal compounds. For a rotationally invariant d-orbital, the local interactions between electrons are expressed in terms of the local Coulomb interaction U and Hund’s coupling JH. The Coulomb interaction prevents electrons from gathering at the same position, and Hund’s coupling distributes the electron to maximize the spin and the orbital angular momenta. The Hund’s coupling often competes against spin-orbit coupling. We explain both the competition between spin-orbit coupling and local interactions in the t52 g orbital via an atomic limit description and the way in which the effects can be revealed in the electronic structure by dynamical mean-field calculation for a simplified lattice Hamiltonian. t2g 궤도는 강한 스핀-궤도 결합 아래 유효 각운동량 jeff 으로 기술된다. 한편 d-궤도는 공간적으로국소화되어 같은 위치의 전자들은 강한 이체 상호작용을 느끼며, 이 상호작용은 전이금속 화합물의금속-절연체 상전이에 중요한 역할을 한다. d-전자궤도가 회전 대칭성을 가질 때, 전자 사이의 국소적상호작용은 쿨롱 상호작용 U 와 훈트 결합 JH 으로 표시할 수 있다. 쿨롱 상호작용은 여러 전자가 한위치에 모이는 것을 방지하며 훈트 결합은 스핀 각운동량과 각운동량을 최대화하는 방향으로 전자 분포를조절하는데, 이중 훈트 결합은 종종 스핀-궤도 결합과 경쟁하게 된다. 이 논문에서는 t2g 궤도에 전자가5개 차있는 t52 g 상황에서 스핀-궤도 결합과 국소적 상호작용의 경쟁관계를 원자극한을 통해 설명하고그러한 경쟁관계가 격자의 전자 들뜸 스펙트럼에 끼치는 영향을 단순화된 모형 해밀토니안에 대한 동적평균장 이론(dynamical mean-field) 계산으로 살펴본다.

Flow modification by inertial particles in a differentially heated cubic cavity

Gereltbyamba, Battsetseg,Lee, Changhoon Elsevier 2019 The International journal of heat and fluid flow Vol.79 No.-

<P><B>Abstract</B></P> <P>In this study, we analyzed particle-laden flow in a differentially heated cubic cavity by using direct numerical simulations and the Lagrangian particle tracking method. The main purpose of this study was to investigate the physical mechanism responsible for the modification of natural convection flow by sedimenting solid particles. Rayleigh number of R a = <SUP> 10 6 </SUP> was considered, and two important parameters, namely, the particle diameter <I>d<SUB>p</SUB> </I> and particle volume fraction Φ<SUB> <I>V</I> </SUB>, were varied in the range of <SUB> d p </SUB> = 25 , 35 , 50 , 75 μ m and <SUB> Φ V </SUB> = 2 × <SUP> 10 − 5 </SUP> , 5 × <SUP> 10 − 5 </SUP> , <SUP> 10 − 4 </SUP> . Extensive numerical investigations were performed by considering the two-way interaction for the following two coupling cases: (i) momentum coupling only; (ii) momentum and thermal coupling between fluid and particles. Behavior of particles, flow modification, and heat transfer characteristics were investigated in detail with the relevant statistics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We investigated the modification of natural convection flow in a differentially heated cavity filled with air by sedimenting small particles by using direct numerical simulation. </LI> <LI> We investigated two cases, namely, momentum coupling and both momentum and thermal coupling. The major parameters were the particle diameter and particle volume fraction. </LI> <LI> For the momentum coupling case, the particles enhanced the circulatory motion, thus making the flow chaotic. Heat transfer is overall slightly suppressed by particles. </LI> <LI> However, for the momentum and thermal coupling case, the thermal energy exchange between the particles and fluid yields completely different behavior than the momentum coupling case. </LI> <LI> The flow became less chaotic which might be attributed to the conjecture that the chaotic motion is suppressed by thermal diffusive processes due to the active thermal interaction between the particles and fluid. </LI> <LI> As a result, heat transfer is suppressed more than the momentum coupling case through the direct and indirect interactions between the sedimenting particles and fluid. </LI> </UL> </P>

지적구조 규명을 위한 키워드서지결합분석 기법에 관한 연구

이재윤,정은경 한국정보관리학회 2022 정보관리학회지 Vol.39 No.1

Intellectual structure analysis, which quantitatively identifies the structure, characteristics, and sub-domains of fields, has rapidly increased in recent years. Analysis techniques traditionally used to conduct intellectual structure analysis research include bibliographic coupling analysis, co-citation analysis, co-occurrence analysis, and author bibliographic coupling analysis. This study proposes a novel intellectual structure analysis method, Keyword Bibliographic Coupling Analysis (KBCA). The Keyword Bibliographic Coupling Analysis (KBCA) is a variation of the author bibliographic coupling analysis, which targets keywords instead of authors. It calculates the number of references shared by two keywords to the degree of coupling between the two keywords. A set of 1,366 articles in the field of ‘Open Data’ searched in the Web of Science were collected using the proposed KBCA technique. A total of 63 keywords that appeared more than 7 times, extracted from 1,366 article sets, were selected as core keywords in the open data field. The intellectual structure presented by the KBCA technique with 63 key keywords identified the main areas of open government and open science and 10 sub-areas. On the other hand, the intellectual structure network of co-occurrence word analysis was found to be insufficient in the overall structure and detailed domain structure. This result can be considered because the KBCA sufficiently measures the relationship between keywords using the degree of bibliographic coupling. 학문의 구조, 특성, 하위 분야 등을 계량적으로 규명하는 지적구조 분석 연구가 최근 급격히 증가하는 추세이다. 지적구조 분석 연구를 수행하기 위하여 전통적으로 사용되는 분석기법은 서지결합분석, 동시인용분석, 단어동시출현분석, 저자서지결합분석 등이다. 이 연구의 목적은 키워드서지결합분석(KBCA, Keyword Bibliographic Coupling Analysis)을 새로운 지적구조 분석 방식으로 제안하고자 한다. 키워드서지결합분석 기법은 저자서지결합분석의 변형으로 저자 대신에 키워드를 표지로 하여 키워드가 공유한 참고문헌의 수를 두 키워드의 주제적 결합 정도로 산정한다. 제안된 키워드서지결합분석 기법을 사용하여 Web of Science에서 검색된 ‘Open Data’ 분야의 1,366건의 논문집합을 대상으로 분석하였다. 1,366건의 논문집합에서 추출된 7회 이상 출현한 63종의 키워드를 오픈데이터 분야의 핵심 키워드로 선정하였다. 63종의 핵심 키워드를 대상으로 키워드서지결합분석 기법으로 제시된 지적구조는 열린정부와 오픈사이언스라는 주된 영역과 10개의 소주제로 규명되었다. 이에 반해 단어동시출현분석의 지적구조 네트워크는 전체 구성과 세부 영역 구조 규명에 있어 미진한 것으로 나타났다. 이러한 결과는 키워드서지결합분석이 키워드 간의 서지결합도를 사용하여 키워드 간의 관계를 풍부하게 측정하기 때문이라고 볼 수 있다.

Correlation Between Fiber Orientation and Geometrical Shrinkage of Injected Parts Under the Influence of Flow-Fiber Coupling Effect

Chao-Tsai Huang,Jun-Zheng Wang,Cheng-Hong Lai,Sheng-Jye Hwang,Po-Wei Huang,Hsin-Shu Peng 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4

Fiber reinforced thermoplastics (FRP) have been widely used in automotive industry. However, how does the flow-fiber coupling effect influence the micro fiber orientation and further affect the geometrical shrinkage of the final part that is not fully understood yet. In this study, a complex center-gated plate has been applied to study the influence of the flow-fiber coupling effect on the fiber orientation variation and the geometrical change through numerical simulation. Then the practical verification through the micro-computed tomography (micro-CT) and image processing technology was carried out. Results show that in the presence of the flow-fiber coupling the required spruce pressure will be higher compared to no coupling case. In addition, the melt flow front pattern will be changed from “convex-flat” to “convex-concave” under the influence of this coupling. Moreover, in the presence of the flow-fiber coupling effect, the wider core width for fiber orientation tensor in the flow direction (A11) can be obtained from upstream to downstream regions for the same model. However, in the downstream region (i.e. in the FR), the flow-fiber coupling effect is more significantly due to the action of less shear rate in that region. Finally, through the measurement of the left–right asymmetrical shape of the FR for Model I (or Model II), the reason is that the flow-fiber coupling effect will switch the fiber orientation from the flow direction (A11) dominate to the cross-flow direction (A22) dominate. This asymmetrical fiber orientation distribution will further create that asymmetrical shrinkage shape of final part. The correlation between fiber orientation and geometrical shrinkage can be achieved.