• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.45-50
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• 2014

A fully packed capillary electrochromatographic (CEC) microchip with an on-column micro-solid phase extraction (SPE) bed for the preconcentration and separation of organic analytes was prepared. A linear microchannel with monodisperse colloidal silica packing was formed on a cyclic olefinic copolymer microchip with two reservoirs on both ends. Silver-cemented silica packing frit structure was formed at the entrance of the microchannel by electroless plating treatment as a base layer. A gold coating was formed on it by reducing $Au^{3+}$ to gold with hydroxylamine. Finally micro-SPE bed was formed by self-assembly adsorption of 1-dodecanethiol on it. Micro-SPE beds were about 100-150 ${\mu}m$ long. Approximately $10^3$ fold sensitivity enhancements for Sulforhodamine B, and Fluorescein in nM concentration levels were possible with 80 s preconcentration. Basic extraction characteristics were studied.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.178-186
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• 2021

The wave power extraction by multiple Wave Energy Converters (WECs) deployed in a Y-shaped Water Channel Resonator (WCR) has been investigated. A WCR consists of a long water channel, and a V-shaped wave guider installed at the entrance of a water channel. If the period of the incident waves coincides with the natural periods of the fluid in a WCR, resonance occurs, as a result, the internal fluid in a WCR is greatly amplified. To estimate the wave power by multiple WECs placed at the antinodal points in a WCR, the heave motion response, time-averaged power, and capture width ratio were calculated for several design parameters. Also, the systematic model tests were conducted in a 2D wave tank. The numerical results are in good agreement with the experimental data. It was verified that a WCR helps the WECs to produce electricity more effectively by amplifying the wave energy in a WCR.

• 대한기계학회논문집B
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• 제22권2호
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• pp.139-152
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• 1998

In the present study, the flow characteristics of developing laminar oscillatory flows in a square -sectional 180 deg. curved duct are investigated experimentally. The experimental study using air in a square-sectional 180 deg. curved duct is carried out to measure velocity distributions with a data acquisition and LDV (Laser Doppler Velocimetry) processing system. In this system, Rotating Machinery Resolver (RMR) and PHASE program are used to obtain the results of unsteady flows. The major flow characteristics of developing oscillatory flows are found by analyzing velocity curves, mean velocity profiles, time-averaged velocity distribution of secondary flow, wall shear stress distributions, and entrance lengths. In a lower dimensionless angular frequency, the axial velocity distribution of laminar oscillatory flow in a curved duct shows a convex shape in a central part and axial symmetry. The maximum value of wall shear stress in a lower dimensionless angular frequency is located in an outside wall, but according to increasing the dimensionless angular frequency, the maximum of wall shear stress is moved to inner wall. The entrance lengths of laminar oscillatory flows in a square-sectional 180 deg. curved duct is obtained to 90 deg. of bended angle of duct in this experimental conditions.

• 한국인터넷방송통신학회논문지
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• 제22권1호
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• pp.171-179
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• 2022

본 논문은 캠퍼스 내 건물별 출입구에 출입명부를 관리할 수 있는 장치를 설치하고, 수집된 데이터를 근거로 코로나19 확진자에 대한 감시 및 추적 시스템을 소개한다. 기존 QR 기반의 전자출입명부는 스마트폰으로 QR 코드를 인식해야 하는 불편함과 건물 내 출입자의 온도를 측정할 수 없다는 단점이 있다. 또한, 국가가 캠퍼스 내의 확진자와 접촉자 정보를 관리함에 있어, 구성원들에게 신속한 정보 공유와 추적이 쉽지 않다. 이는 확진자와 밀접 접촉한 이가 또 다른 확진자를 만드는 경우를 초래할 수 있다. 따라서, 본 논문에서는 이에 대응하기 위해 얼굴 인식 기능과 온도센서를 포함한 장치를 캠퍼스 내 건물 출입구에 설치하고, 관리자가 실시간으로 건물별 구성원들의 출입현황을 모니터링하여 신속하게 추적할 수 있는 기능을 소개한다.

• 한국항해항만학회지
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• 제27권6호
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• pp.677-682
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• 2003

The long-period gravity wave, the wave period from some ten seconds to some minutes, induces not only the big sway of a ship moored and berthed in the harbor due to the horizontal long-distance motion of a water but also strong exfoliated flow and vortices near the harbor entrance. They muse serious problems on the safety navigation of vessels entering and leaving the harbor, but this gravity wave has not been searched sufficiently yet. Then it is quite important to reveal the characteristics of this long-period gravity wave ana to solve various problems induced by this wave. The long-period gravity wave measurement system with arrayed buoys installed the kinematic GPS was already proposed, which provides the precise propagating direction of the long-period gravity wave. In this paper, the observation results of the wave measurement system are shown by the MUSIC method And the propagating wave direction was estimated precisely enough in comparison with other results used other method.

• 수산해양교육연구
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• 제25권1호
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• pp.40-52
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• 2013

The purpose of this study is to explore improving ways of screening of self-directed learning in self-governing high schools for expanding self-initiated learning screening system. To achieve the above aim, it was used survey method to 99 admission teachers of 12 self-governing high schools and analyzed responses with SPSS program. The research findings are as follows. To expand self-initiated learning screening system in self-governing high schools, it needs to obtain admission members of entrance committee, pooling of external screening members, quick decision of school admission members, increasing payment, training and understanding of the system and consideration of admission documents and study plan. Some improving ways of the expanding of self-initiated learning screening may be listed as follows: 1) development of screening model for self-governing schools 2) policy consideration for self-governing public high school 3) expanding autonomy of school 4) supporting budget 5) sharing of operation case and reinforcement of public relations.

• 전기학회논문지
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• 제65권12호
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• pp.2046-2052
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• 2016

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

• 영재교육연구
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• 제22권4호
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• pp.929-942
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• 2012

본 연구는 대학부설 과학영재교육원에서 관찰 추천제에 의한 선발 및 융합과학전공의 도입 후에 학생 선발과 교육 내용 구성이 어느 정도 타당하게 진행되었는지를 분석해 보고 문제점을 파악하여, 향후 과학영재교육원의 학생 선발과 융합과학 전공 운영을 위한 제안을 하고자 하는 목적에서 실시되었다. 이를 위해 한 대학부설 과학영재교육원 융합과학전공의 입학사정 결과를 분석해 보고, 입학 성적과 입학 후 융합과학전공에서의 수행 능력과의 상관관계를 분석해 보았다. 그 결과 관찰 추천제가 추천자 및 심사자 대한 의존도가 높은 선발 방식임에도 불구하고 심사자들 사이의 관점이 매우 다른 것으로 나타났으며, 선발과 입학 후 교육이 일관성 있게 이루어지지 못했다는 문제점이 나타났다.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제25권4호
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• pp.629-639
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• 2011

최근 공과대학 학생들에게 대학수학의 중요성이 부각되고 있는 반면, 제7차 수학과교육과정의 인문계 수학에는 미분적분이 포함되어 있지 않고, 많은 중위권 대학의 입학전형에서 교차지원을 허용하기 때문에 공과대학 대학수학의 교수학습에서 많은 어려움이 발생한다. 본 연구에서는 중위권 공과대학 신입생들의 수학 기초학력과 대학수학능력시험수리영역 성적의 관계를 조사하여 교차지원을 허용하는 입학전형 제도의 문제점을 실증적으로 밝히는데 그 의의를 두었으며, 이를 위하여 2010학년도 A대학교 공과대학 신입생들을 대상으로 대학수학능력시험 수리영역 성적과 수학 기초학력평가 및 대학수학 교과목의 성적을 비교 분석하였다.

• 한국산업보건학회지
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• 제31권4호
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• pp.503-509
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• 2021

Objectives: The utility of the system was analyzed by applying the smart safety technology system to the aging pipe rehabilitation facility construction classified as a confined space. Methods: Smart safety management system was applied to a site where the aging pipe rehabilitation work was in progress. The working environment was measured for 25 days, and the toxic gas saturation was analyzed according to the working time and working place. Results: Based on the measured results, two characteristic environmental changes in the confined space were confirmed. First, when working inside an aging pipe, the tendency of carbon dioxide saturation increases with working time and the number of workers. Second, oxygen decreases when working in a space away from the entrance. Conclusions: Various applications of smart safety technology have been confirmed based on the measured data, and this is expected to be useful for environmental characteristic analysis and safety management when applied to a confined space composed with various conditions in the future.