• 한국해양공학회지
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• 제32권4호
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• pp.244-252
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• 2018

This paper provides quantification of the effects of the turbulence model and grid refinement on the analysis of tip vortex flows by using the RANS(Reynolds averaged Navier-Stokes) method. Numerical simulations of the tip vortex flows of the NACA $66_2$-415 elliptic hydrofoil were conducted, and two turbulence models for RANS closure were tested, i.e., the Realizable $k-{\varepsilon}$ model and the Reynolds stress transport model. Numerical results were compared with available experimental data, and it was shown that the data for the Reynolds stress transport model that were computed on the finest grid system had better agreement in reproducing the development and propagation of the tip vortex. The Realizable $k-{\varepsilon}$ model overestimated the turbulence level in the vortex core and showed a diffusive behavior of the tip vortex. The tip vortex cavitation on the hydrofoil and its trajectory also showed good agreement between the current numerical results that were obtained using the Reynolds stress transport model and the results observed in the experiment.

• Journal of Electrochemical Science and Technology
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• 제5권1호
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• pp.1-18
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• 2014

Li-air cell is an exotic type of energy storage and conversion device considered to be half battery and half fuel cell. Its successful commercialization highly depends on the timely development of key components. Among these key components, the catalyst (i.e., the core portion of the air electrode) is of critical importance and of the upmost priority. Indeed, it is expected that these catalysts will have a direct and dramatic impact on the Li-air cell's performance by reducing overpotentials, as well as by enhancing the overall capacity and cycle life of Li-air cells. Unfortunately, the technological advancement related to catalysts is sluggish at present. Based on the insights gained from this review, this sluggishness is due to challenges in both the commercialization of the catalyst, and the fundamental studies pertaining to its development. Challenges in the commercialization of the catalyst can be summarized as 1) the identification of superior materials for Li-air cell catalysts, 2) the development of fundamental, material-based assessments for potential catalyst materials, 3) the achievement of a reduction in both cost and time concerning the design of the Li-air cell catalysts. As for the challenges concerning the fundamental studies of Li-air cell catalysts, they are 1) the development of experimental techniques for determining both the nano and micro structure of catalysts, 2) the attainment of both repeatable and verifiable experimental characteristics of catalyst degradation, 3) the development of the predictive capability pertaining to the performance of the catalyst using fundamental material properties. Therefore, under the current circumstances, it is going to be an extremely daunting task to develop appropriate catalysts for the commercialization of Li-air batteries; at least within the foreseeable future. Regardless, nano materials are expected to play a crucial role in this field.

• 한국의류산업학회지
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• 제13권5호
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• pp.672-678
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• 2011

This was written based on the type and structure of korean man's waist belt in the early and middle era of the Chosun era. The waist belt was excavated from the Mokdaldong in the Daejeon city. The types of korean man's waist belt in the Chosun era were classified into Wondahae (i.e., round shape belt) and Gwangdahae. The Wondahae consist of two types which are circle shaped and straight types. The circle shaped wondahae contain one fringe in the main body of the belt and its joint part is decorated with a small network such as lacing decoration with the size about 1 cm around. The shape of the Wondahae has been changed from the circle shaped into the straight types and also has a tendency to be wider and longer as time went by. The standard form of the Gwangdahae is straight with about 2-3 cm width and elaborated by lacelike fringe as well. This also has a tendency to be wider starting from the 1600s show. The structure of this belts were divided into braid and ornament parts. The ornament part was constructed with the lacelike netting and fringe parts. The sophisticated craft techniques have a great decorative beauty. Through an analysis of FT-IR, the materials of those three belt are known which are made of the silk and the core thread was filled with cotton. Moreover, it can be confirmed that the glitter material of the ornament part were designed with gold foil and has been analyzed with SEM-EDX.

• 한국도서관정보학회지
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• 제43권2호
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• pp.157-178
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• 2012

본 연구의 목적은 질적 다방법을 적용하여 사서의 직업사회화 경험 과정을 통합적으로 도출하고, 그 이해를 증진하고자 하였다. 순차적으로 이루어진 일련의 3개의 질적 선행연구에서 이론적 표집에 의해 수집된 총42명의 현직 사서(사서교사)들의 심층면담자료를 질적 다방법 접근의 최종 통합방법으로서 근거이론 방법을 적용하여 분석하였다. 그 결과, 사서의 직업사회화 경험의 전체 과정을 이끌고 통합하는 핵심범주는 '사회적 인정 추구하기' 이며, 그 과정은 '적응하기', '주변부임을 절감하기', '역할 인식하기', '발전 모색하기', '전문성 구현하기', '가치 재발견하기', '전문성 발현하기'로 도출되었다. 특히, '주변부임을 절감하기' 과정은 사서의 직업사회화를 나타내는 독특하고, 핵심적이며 강렬한 과정으로 나타났으며, 이는 사서들이 지각하는 이중적 직업인식 및 소외의식을 반영하는 것이라고 할 수 있다. 각 과정의 특색과 사회화 전략을 논의하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.432.2-432.2
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• 2014

Recently, colloidal core/shell type quantum dots lighting-emitting diodes (QDLEDs) have been extensively studied and developed for the future of optoelectronic applications. In the work, we fabricate an inverted CdSe/ZnS quantum dot (QD) based light-emitting diodes (QDLED)[1]. In order to reduce work function of indium tin oxide (ITO) electrode for inverted structure, a very thin (<10 nm) polyethylenimine ethoxylated (PEIE) is used as surface modifier[2] instead of conventional metal oxide electron injection layer. The PEIE layer substantially reduces the work function of ITO electrodes which is estimated to be 3.08 eV by ultraviolet photoemission spectroscopy (UPS). From transmission electron microscopy (TEM) study, CdSe/ZnS QDs are uniformly distributed and formed by a monolayer on PEIE layer. In this inverted QD LED, two kinds of hybrid organic materials, [poly (9,9-di-n-octyl-fluorene-alt-benzothiadiazolo)(F8BT) + poly(N,N'-bis (4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD)] and [4,4'-N,N'-dicarbazole-biphenyl (CBP) + poly-TPD], were adopted as hole transport layer having high highest occupied molecular orbital (HOMO) level for improving hole transport ability. At a low-operating voltage of 8 V, the device emits orange and red spectral radiation with high brightness up to 2450 and 1420 cd/m2, and luminance efficacy of 1.4 cd/A and 0.89 cd/A, respectively, at 7 V applied bias. Also, the carrier transport mechanisms for the QD LEDs are described by using several models to fit the experimental I-V data.

• 한국의상디자인학회지
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• 제21권4호
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• pp.195-211
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• 2019

In this paper, Capstone Design Education Program Learning Model was developed and recommended in order to foster convergent talents armed with practical competences and real cooperative capabilities. In this era of convergence and creativity, the fashion world needs human resources with cooperative skills and true professional abilities. A case analysis, an in-depth interview, and 1,2 test method were used for data acquisition and analysis. The summary of this study is described below. First, this program needs to complement the NCS fashion design learning module. Second, material changes to creativity and practical competencies - knowledge, skills, and attitudes - of the students are assessed after applying Capstone Design to the NCS fashion design learning model. Third, the process of converging fashion curriculum with IT and electronic technology, developing a fashion design learning program, and applying the Capstone Design was tested to prove the effectiveness of convergent fashion design education. Among the changes observed between the trial and control groups, it was confirmed that sub-factors of creative personality, i.e. self-assurance and openness, were increased along with knowledge, core competences including communication capability, and self-directed learning capability. The greatest improvement on the technological side was observed in IT literacy while ability to respond to changes was also increased. Besides, effects were demonstrated in behavioral factors such as initiative, spirit of challenge, experience, and openness. Lastly, the Capstone Design Education Program Learning Model was proposed in order to foster convergent talents in the fashion world.

• 지질공학
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• 제17권4호
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• pp.517-523
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• 2007

이 연구에서는 초정지역의 충적층 지하수와 관련된 풍화대분포를 파악하고 단층파쇄대 조사를 위해 복합물리탐사(탄성파굴절법, 전기비저항, 지하투과레이더탐사)를 수행하였다. 탄성파속도 정보로부터 풍화대는 대상지역의 남서부로 갈수록 깊어지는 것으로 나타나는데 기반암까지의 심도 즉 풍화대의 두께는 또한 기존의 시추자료 및 지하수위 자료와 거의 일치한다. 소규모 단층과 관련된 파쇄대 조사에서는 탄성파굴절법, 전기비저항, 레이더탐사 자료를 속도와 비저항 구조를 복합적으로 천부까지 해석하여 단층파쇄대의 지표 경계등을 파악하였다. 복합 지구물리탐사로 정확히 제시된 풍화대와 파쇄대 등에 대한 정보는 충적층 지하수의 분포를 알아내는데 충분히 활용될 수 있을 것으로 보인다.

• 한국컴퓨터정보학회논문지
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• 제5권2호
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• pp.60-70
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• 2000

최근 컴퓨터 기술의 발전으로 인해 영상을 효율적으로 검색할 수 있는 영상 검색 시스템이 정보화 사회의 중요한 핵심 기술로 대두되고 있다. 본 논문에서는 내용기반 영상 데이터 검색을 위한 계층적 영상검색 시스템을 구현하였다. 1단계에서는 색상 정보를 위해서 Striker 등이 제시한 색상 분포 특성을 이용한 색인 방법의 문제점을 보완하여 지역 색상 분포 특성을 고려한 색인 방법을 사용하여 1차로 영상을 대 분류한다. 2단계에서는 1단계에서 대 분류된 집단 영상들에 대하여 2차로 모양 정보를 이용하여 사용자가 질의한 영상과 유사한 영상을 최종적으로 검색한다 모양 정보를 위해서는 기존 불변 모멘트의 문제점인 많은 연산량과. Jain 등이 제시한 방향 히스토그램 인터섹션 방법에서 제기된 회전에 민감하다는 문제점을 해결하기 위해 물체의 윤곽선에 해당하는 화소들만을 대상으로 연산을 수행하는 향상된 불변 모멘트(Improved Moment Invariants : IMI)를 이용한다. 실험 영상으로 300개의 자동차 영상을 사용하여 기존 방법들과의 비교 실험을 통해 향상된 검색 결과를 얻을 수 있었다.

• 대한조선학회논문집
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• 제53권5호
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• pp.343-352
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• 2016

In this study, a pre-swirl duct for the 180,000 DWT bulk carrier has been designed from a propulsion standpoint using CFD. The stern duct - designed by NMRI - was selected as the initial duct. The objective function is to minimize the value of delivered power in model scale. Design variables of the duct include duct angle, diameter, chord length, and vertical and horizontal displacements from the center. Design variables of the stators are blade number, arrangement angle, chord length, and pitch angle. A parametric design was carried out with the objective function obtained using CFD. Reynolds averaged Navier-Stokes equations have been solved; and the Reynolds stress model applied for the turbulent closure. A double body model is used for the treatment of free-surface. MRF and sliding mesh models have been applied to simulate the actuating propeller. A self-propulsion point has been obtained from the results of towing and self-propelled computations, i.e., form factor obtained from towing computation and towing forces obtained from self-propelled computations of two propeller rotating speeds. The reduction rate of the delivered power of the improved stern duct is 2.9%, whereas that of the initial stern duct is 1.3%. The pre-swirl duct with one inner stator in upper starboard and three outer stators in portside has been designed. The delivered power due to the designed pre-swirl duct is reduced by 5.8%.

• 한국수학교육학회지시리즈A:수학교육
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• 제43권4호
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• pp.321-335
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• 2004

This study looked into the procedures of and the status on the implementation of the new 7th national curriculum at the elementary school level. It examined the processes taken by the local boards of education in due course of facilitating the schools with the new curriculum implementation. More specifically the study examined, 1) the degree to which the particular innovation(i.e., student-centered, flexible and autonomous school-based curriculum, etc.) is being implemented as planned; and 2) how it is being implemented. It conducted a situation-oriented analysis in cooperation with three local boards of education. Classroom observations, teacher interviews, questionnaires for teachers and supervisors were utilized and the three major criteria of interpreting the result were the three core concepts of the 7th national curriculum, that is, the degree of '(1) reorganization, (2)student-centeredness and (3)diversification/ specialization' of the curriculum. Detailed documentation on the processes of the local bureaus of education and on the classroom practices are made in order to provide schools and policy makers with relevant and practical suggestions for further improvement of curriculum implementation. Ultimately, The greater the awareness of the intention of the new curriculum on the part of both the staff at the local school boards and teachers, the greater the degree of implementation. And the higher the quality of planning to meet problems, the greater the degree of implementation. Continuous efforts are needed to involve teachers in the process of curriculum implementation. The greater the active support of the teachers, the greater the degree of implementation.