• Steel and Composite Structures
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• 제47권2호
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• pp.167-184
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• 2023

In this study, a new recentering friction device (RFD) to retrofit steel moment frame structures is introduced. The device provides both self-centering and energy dissipation capabilities for the retrofitted structure. A hybrid performance-based seismic design procedure considering multiple limit states is proposed for designing the device and the retrofitted structure. The design of the RFD is achieved by modifying the conventional performance-based seismic design (PBSD) procedure using computational intelligence techniques, namely, genetic algorithm (GA) and artificial neural network (ANN). Numerous nonlinear time-history response analyses (NLTHAs) are conducted on multi-degree of freedom (MDOF) and single-degree of freedom (SDOF) systems to train and validate the ANN to achieve high prediction accuracy. The proposed procedure and the new RFD are assessed using 2D and 3D models globally and locally. Globally, the effectiveness of the proposed device is assessed by conducting NLTHAs to check the maximum inter-story drift ratio (MIDR). Seismic fragilities of the retrofitted models are investigated by constructing fragility curves of the models for different limit states. After that, seismic life cycle cost (LCC) is estimated for the models with and without the retrofit. Locally, the stress concentration at the contact point of the RFD and the existing steel frame is checked being within acceptable limits using finite element modeling (FEM). The RFD showed its effectiveness in minimizing MIDR and eliminating residual drift for low to mid-rise steel frames models tested. GA and ANN proved to be crucial integrated parts in the modified PBSD to achieve the required seismic performance at different limit states with reasonable computational cost. ANN showed a very high prediction accuracy for transformation between MDOF and SDOF systems. Also, the proposed retrofit showed its efficiency in enhancing the seismic fragility and reducing the LCC significantly compared to the un-retrofitted models.

• Composites Research
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• 제19권2호
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• pp.28-34
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• 2006

고온자전합성법과 스파크 플라즈마 소결법으로 여러 가지 $TiB_2$ 함유량을 갖는 $Cu-TiB_2$ 금속복합재료를 제조하였다. 점용접 전극과 미끄럼 접촉재로 사용하기 위해 인장특성, 경도, 마모저항 등의 물성치를 조사하였다. 강화재의 형상, 크기, 부피분율 등에 의해 복합재료의 특성이 달라지므로 유효물성치를 예측하기 위한 모델링이 필수적이다. 유한요소해석결과 유효탄성 계수가 실험치와 일치하는 것을 확인하였고 Eshelby 모델, Mori-Tanaka의 평균장 이론이 결합된 Eshelby 모델, 혼합법칙 등으로 복합재료의 탄성계수를 예측한 결과 Mori-Tanaka의 평균장 이론이 결합된 Eshelby 모델이 실험치를 사장 잘 묘사하는 것으로 나타났다.

• 영어영문학
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• 제58권6호
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• pp.1041-1061
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• 2012

In the late nineteenth century, British colonial activities became aggressive and annexationist in the tropics, including the Southeast Asian Archipelago, which reflected the historical circumstances of both increasing resistance from the indigenous and severe competition among European powers. Interestingly, the change in English colonial policy toward an annexationist or imperialist vision adopted the motto of a civilizing mission, which was founded on the anthropological assumption that the white English were civilized, while the non-white indigenous were savage. The assumption developed into colonial discourse through systematic gathering of anthropological knowledge about the peripheries of the Empire. The knowledge system was flawed, which stressed the differences of the peripheral populations from the English and served as an inverted discourse on the Imperial Self rather than the description of the Other. Furthermore, the natives were heterogeneous, which rendered indistinct the racial and cultural differences between the English and the natives. Still, the aboriginals called Malays, who were comprised of many ethnic subgroups, needed to be deemed savage or inferior by the English in order to justify the English civilizing work or imperial ambition. Put differently, the representation of the English as civilized necessitated the (mis)representation of the natives as savage. In this context, Clifford's works contribute to systematic misrepresentation of the Malays, on which colonial discourse is founded, though not without self-contradiction. On the other hand, Conrad's novels that are set in the Malay Archipelago resort to a strategic misrepresentation that reveals the relativity of the discourse. Exploring the dilemma of denationalization to various degrees, Conrad's Malay texts problematize the (mis)representation of the indigenous as inferior, which is the basis of English claim to superiority.

• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.1-8
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• 2023

해양 및 수리구조물은 수분침투뿐만 아니라 해양의생물의 부착 등에 의해서도 내구손상이 발생하게 된다. 따라서 본 연구에서는 해양 콘크리트 등을 위해 자가세척기능을 갖는 방오 코팅제를 개발하고자 하였다. AKD와 셀룰로오스 나노섬유 및 BADGE를 혼합한 방오코팅제를 접촉각 140°내외의 소수성과 기울임각 15°에서 충분한 방오성능 확보한 것으로 확인하였다. 표면의 내마모성 시험에서는 최대 0.015g의 손실만이 발생하는 것으로 나타났다. 내구성 실험에서도 염소이온투과시험결과 코팅제가 도포된 변수에서는 염소이온의 투가가 거의 발생하지 않았으며, 탄산화와 동결융해 손상 또한 역시 거의 발생하지 않아 콘크리트의 내구성 확보에서도 효과가 있는 것으로 분석되었다.

• 영재교육연구
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• 제20권1호
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• pp.317-346
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• 2010

본 연구는 초등학교 과학영재수업을 담당하는 교사들의 과학 영재수업 및 영재아에 대한 인식 변화와 교사들의 실제 수업 및 동료교사 간의 대화를 통해 실천적 지식의 변화과정을 알아보는 것을 목적으로 하고 있다. 연구대상으로 수업개선을 희망하는 초등교사 2명(A와 B교사)을 선정하였고, 그 교사들은 수업 및 수업대화를 통해 수업에 대한 자기성찰과정을 경험하였다. 교직경력 10년차인 A교사는 학부 때부터 영재아 관찰을 통해 영재를 접해왔고 평소에도 영재나 과학수업에 관심을 많이 갖고 있어 대학원에 진학하였다. 그에 비해 B교사는 교직경력이 3년차이며 대학원에 진학한 이후 영재아를 접해 본 교사이다. 본 연구의 결과는 다음과 같다. 좋은 수업에 대한 확고한 신념과 영재에 관한 지식이 선행되어 있는 A교사는 자신의 실제 교실 수업 경험으로부터 반성적 성찰을 통해 영재수업에 대한 실천적 지식이 발달되는 것을 알 수 있었다. 또한 수업관찰과 동료교사와의 수업대화를 통해 고민한 부분에 대하여는 교수방법을 변경하거나 교과내용지식을 보강하는 등 실천적 지식이 다음 수업에 실제적으로 반영되어 나타났다. 그러나 영재에 관한 지식이 선행되지 않은 B교사는 자신의 수업성찰이나 수업 경험이라기보다는 동료교사와의 대화를 통해 실천적 지식의 발달이 이루어졌으며 형성된 실천적 지식을 다음 수업에 반영하는데 다소 어려움을 겪는 듯하였다. 이러한 결과로부터 교사가 가지고 있는 신념, 가치관, 경험, 지식 등에 따라 실천적 지식의 변화과정이나 형성과정이 다르다는 것을 알 수 있다. 수업, 수업관찰, 동료교사와의 수업대화를 통한 자기 수업에 대한 성찰은 초등영재 담당교사가 실천적 지식을 형성하여 수업전문성을 향상시키기에 좋은 방법이 되므로 영재 교사교육 프로그램에서 모의수업, 자기수업반성, 수업대화를 통해 수업에 대한 실천적 지식을 형성할 수 있는 기회를 제공하는 데 활용될 수 있을 것이다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.143-144
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• 2002

A series of alcohols with perfluorinated segments $F(CF_2)_m(CH_2)_n-OH$, with m=8, 10 and n=4, 6, 10, were synthesized. First, the alcohols were reacted with fatty acid to produce several esters $(F(CF_2)_m(CH_2)-OOC-R$ with m=8, 10 and n=2, 4, 8,) containing perfluoro group by condensation reaction, and characterized by FT-IR, GC, and surface tension. The esters were soluble in ethyl ether, toluene, hexane, ethyl acetate, chloroform, and acetone, but insoluble in methyl alcohol, ethyl alcohol and isopropyl alcohol. Preliminary experiments on 1,2-dichloroethane solutions showed a remarkable decrease of surface tension upon addition of the esters. Also, the esters films ranged from 100 to $122^{\circ}$, depending on the structure of fatty acid esters. As the separate experiment, the water-repellency of coated paper and cotton was evaluated. As a result, the water droplet dropped in surface was not permeated for two weeks.

• 한국세라믹학회지
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• 제49권5호
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• pp.417-422
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• 2012

Copper nano particles have been considered as the materials for conductive ink due to its good thermal, electrical conductivity and low cost. However, copper nanoparticles oxidize easily, decreasing dispersion stability and electrical conductivity. Therefore, it is important to develop a method to minimize oxidation of copper nano particles to improve its dispersion stability property in copper nano ink. In this study, copper nano particles were coated with 1-Octanethiol VSAM(Vaporized Self Assembled Multilayers) to prevent oxidation and coated copper powders were dispersed in conductive ink successfully by studying its relationship of different chain length of solvents to 1-Octanethiol coating layer to fabricate nano ink. Various alcohol solvents, such as 1-Hexanol, 1-Octanol, and 1-Decanol were used. The coating layer was observed using FESEM and TEM. Furthermore, dispersion of copper nano particles in nano inks, was characterized using Turbiscan analyzer, viscometer, and contact angle measurement tool.

• 영어어문교육
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• 제11권1호
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• pp.17-36
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• 2005

The purpose of this study is to examine the ways in which CALL apply to enhance the motivational aspects of second language learning. Theories relevant to social, cognitive, and affective foundations of motivation are first reviewed to demonstrate the important role of motivational influences in improving learners' affect and achievements. Then, implications arising from such theories in strengthening the motivational aspects of CALL are explicated in the second part. With the spread of computer technology in language classrooms, the innovative role of CALL in the development and maintenance of intrinsic motivation can be illustrated. Specifically, CALL may provide cognitively supportive instruction geared towards improving students' performance. Also, it has been reported from the affective perspective that CALL can captivate learners' attention, promote their feelings and expectations of success, improve perceptions of control, and increase positive attributions to effort and ability. Finally, from a social learning perspective, CALL may enhance learners' self-efficacy and foster their achievement and positive affect through social interactions, proximal goal-setting, and attributional feedback. In the framework of CALL, students seem to be benefited by the immediacy and authenticity of contact with target languages and cultures made at their choices and decisions.

• 대한간호학회지
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• 제25권2호
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• pp.330-340
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• 1995

This study was conducted to find out the degree of paternal attachment to neonate, and to identify factors affecting paternal attachment. The main purpose was to make the base data for nursing intervention to improve parternal attachment. The subjects of this study were 20 fathers whose partners have delivered premature neonate and 30 fathers whose partners have delivered normal neonate in 3 university hospitals in Seoul. Data were collected from Feb. 10 to Apr. 10 1994 by self report questionaires. The instrument for this study was based on 7 kinds of characteristics of paternal attachment by Greenberg St Morris(1974), and developed by re-searcher The statistical methods for data analysis were percentage, mean, standard deviation, 1-test, ANOVA with S.P.S.S. program. The conclusions are as follows. 1. Fathers had the high degree of paternal attachent to neonate, but were afraid of active touch. 2. The factors that affect paternal attachment were delivery odor, past experience about own father except delivery pattern, pregnancy plan, sex of nonate. 3. There were not significant correlations between paternal attachment and early visual contact frequency of father-neonate. 4. In the degree of paternal attachment, though normal neonate father showed somewhat higher result than premature neonate father, there was not statistically significant difference between two groups(t=-1.83, P=0.076). But in the character of tactail awarness there were significant differences between two groups, hence nursing interventions are needed to help the premature neonate's father bring early tactile con-tact. Pother research about factors affecting paternal attachment to neonate and high risk neonate as well as low birth weight neonate is reguired.

• The Journal of Korean Physical Therapy
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• 제10권1호
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• pp.127-138
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• 1998

This study was carried out tn invstigate and compare biomechanical characteristics during free speed gait in hemiplegic patients after stroke who took therapeutic exercise by analyzing kinematic and kinetic data in the sagital plane and electromyographic data. Six patients($41\~69$ years old) and age-matched six volunteers in good health(51-61 years old) wire studied. The patients were sorted into two groups, depending on their self-speed of walking : fast speed group(3 patients) and slow speed group(3 patients). The results were as fellows. : 1. In spatio-temparal parameters, affected and unaffected side of fast group showed symetry but blew group showed asymetry of single limb support, opposite foot contact and stance phase (p<0.05). Compared with normal group, patient group showed slower velocity, shoter stride length and longer double limb support (p<0.05). 2. In the pelvic anterior tilt, patient group showed lower valued than normal group. It. In the ground reaction force-vertical force, fast group showed similar double peak gragh compared with normal group, butvslow group showed lower values without double peak (p<0.05).