• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.193-196
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• 2002

The relativistic theory has not been properly taken up by the marine hydrodynamicists. To take on a relativistic view, we confine ourselves to a simple vector case of a wave train in spacetime, to be shown to represent a sound wave or a surface wave, and bring in an observer who is travelling on another platform. We are interested in relative position of each event on these two worldlines. It, then, will be shown that the velocity, the acceleration, the encounter frequency, the group velocity, and the time and the space distance between the wave and the observer on the worldlines should all be derivable in principle. This is interpreted to mean that we really have the relativistic events taking place with different values of time dilation in the sense of 'spacetime', and that the well-known ${\lceil}special Theory of Relativity{\rfloor}$ applies just as well in hydrodynamic waves.

• 한국조경학회지
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• 제30권6호
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• pp.79-97
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• 2003

The purpose of this paper is to analyze a causal model determining social carrying capacity(SCC) in natural parks, to answer the research question: What is the mechanism for determining SCC in natural parks (NP)\ulcorner After reviewing the literature on SCC and recreation activities in Korean natural parks, we constructed a conceptual framework and formulated the hypothesis of this research. We obtained data through a questionnaire which surveyed 487 visitors at 6 of the 73 NP in Korea during 2001, based on a stratified sampling method. We analyzed the data using descriptive statistical methods, the mean difference test, Pearson's correlation analysis, and path analysis method. We found that 1) The direct effect of resources, activity space(AS), visitor's expectation(VE), encounter, crowding, damage of resources(DR), maintenance condition of resources and facility(MCRF) to SCC are 3.45, 3.62, 2.75, 2.72, 1.32, and 4.77 times more important than that of crowding, respectively, while the indirect effect of resources, AS, VE, encounter, and DR to SCC is 13.03, 11.19, 3.34, 1.3, 2.05, 1.10, 0.05 and 2.30 times more important then that of crowding, respectively, 2) Causal effects of resources, facility, AS, VE, number of visitors(NV), encounter, crowding, VM, DR, and MCRF to SCC turned out to have 0.3523, 0.3321, 0.1751, 0.1465, 0.0307, 0.0762, 0.0604, -0.0510, -0.1177 and 0.2165, respectively, and 3) The causal effect of activity base(AB) and activity atmosphere(AA) to SCC turned out to have 2.57 and 1.1 times higher than that of MCRF, respectively. The research results suggest that 1) this conceptual framework is highly useful for the development of substantive theory and methodology; 2) management issues of AA and MCRF turned out to have 0.81 times in SCC that of AB, i.e, SCC can be significantly improved from control of AA and MCRF; and 3) supply of excellent resources and convenient facilities is needed to increase social carrying capacity. It is recommended that more empirical studies be performed in the future according to the season, visitor characteristics, and AS by NP.

• 대한조선학회지
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• 제21권3호
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• pp.27-34
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• 1984

When a ship is travelling in following seas, the encounter frequency is reduced to be very low. In that case broaching phenomenon is most likely to occur, and it may be due to wave exciting forces acting on ships. It is thought that the wave exciting forces acting on ships in following seas almost consist of two components. One is hydrostatic force due to Froude-Krylov hypothesis, and the other is hydrodynamic lift force due to orbital motion of water particles below the wave surface. In the present paper, the emphasis is laid upon wave exciting sway force, yaw moment and roll moment acting on ships in following seas. The authers take the case that the component of ship speed in the direction of wave propagation is equal to the wave celerity, i.e., the encounter frequency is zero. Hydrostatic force components are calculated by line integral method on Lewis form plane, and hydrodynamic lift components are calculated by lifting surface theory. Furthermore captive model tests are carried out in regular following waves generated by means of a wave making board. Through the comparison between calculated and measured values, it is confirmed that the wave exciting forces acting on ships in following seas can be predicted in terms of present method to a certain extent.

• 문화기술의 융합
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• 제9권3호
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• pp.811-816
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• 2023

기후 위기가 대두되며 최근 한국에서도 기후 재난이 선명하게 체감되고 있다. 특히 2022년 여름에 발생한 태풍 '힌남노'는 가공할만한 위력으로 많은 사람이 위기감을 느끼게 했다. 이러한 상황에서 아동들은 재난 상황에 대한 경험과 대처 능력이 부족하여 작은 위기에도 큰 피해를 받을 가능성이 높다. 본 논문에서는 아동들의 재난 대처 훈련을 지원하는 재난 상황 대처법 학습 애플리케이션을 소개한다. 상황학습이론과 아동 재난안전교육에 대한 연구 결과를 바탕으로 설계된 본 시스템에서는 다양한 에피소드를 제작하여 재난 상황을 접하도록 교육한다. 아동은 에피소드 진행 중 선택지를 고르며 에피소드에 참여할 수 있고, 이는 에피소드 완료후 그림일기에 반영된다. 그림일기 속에 자연스럽게 정보를 제공하여 아동은 재난 상황에서의 대처법에 대해 접할 수있다. 본 시스템을 통해 아동은 본인이 접할 수 있는 재난 상황에서 판단력을 기르고, 성인의 도움 밖에서 기본적인 안전을 확보하는 능력을 지닐 수 있을 것으로 기대된다.

• Asian Journal for Public Opinion Research
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• 제7권4호
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• pp.226-250
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• 2019

The purpose of this study is to explore whether the perceptions of materialistic realities of South Korean university students can be explained by individual experience and media use. We examined: 1) relative consequences of awareness of discrimination experience and amounts of time spent on genre-specific media on perceptions of materialistic realities, 2) whether cultural orientation (allocentrism, self-monitoring, and masculinity) influences explanatory factors of awareness of discrimination experience, 3) conditions of countervailing responses to materialistic reality. As a result of analyzing the online survey data of 330 university students in Seoul, the amount of time spent on the beauty or fashion genre and awareness of discrimination experience explained the perceptions of materialist reality in Korean society. Although the perceptions that affected the accommodative response did not affect countervailing response, innovativeness had an interaction effect with perceptions of materialist reality in only countervailing response. Finally, the implications of these findings were discussed.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제14권3호
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• pp.263-279
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• 2010

Teachers' personal knowledge (PK) is an element in their pedagogic-practical knowledge. This study exposes the PK of primary school mathematics teachers regarding solid geometry through reflection. Students are exposed to solid geometry on various levels, from kindergarten age and above. Previous studies attested to the fact that students encounter difficulties-strong dislike and fear engendered by geometry. A good number of teachers have strong dislike to solid geometry, as well. Therefore, those engaged in teaching the subject must address the problem and try to overcome these difficulties. In this paper we have introduced the reflective process among teachers in primary school, including application of Van-Hiele's theory to solid geometry.

• 한국의류학회지
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• 제30권6호
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• pp.961-970
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• 2006

This study attempted to understand post-purchase consumer return experiences which had not received much attention in consumer behavior research. As a first step to understand return experiences from consumers' viewpoint, the study took an exploratory approach and identified themes and patterns from subjective consumer experiences. Whenever possible, attribution theory was applied to interpret the identified patterns. A total of 99 cases were collected from an open-ended questionnaire and analyzed based on a qualitative method. The reasons of product return was classified into five groups: changing mind; product defects; unsuitable products; products not expected; and for a better deal. External attribution was observed for return decisions caused by consumers' changed mind as well as by product defects. Dissatisfaction with defected products seemed to be intensified or reduced by service failure or success in the post-purchase service encounter. Consumer expectation and situations seemed to affect this process. Overall, the study supported attribution theory in the post-purchase return experience, and insights for research questions were proposed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.909-914
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• 1988

The structure of a digital controller based on modern control theory is more complex than that of a PID controller. In implementing the digital control of an actual system by using the digital controller, we often encounter gaps between theory and practice e.g. quantization error, sampling error, modeling error, contaminated noise etc. In such cases, simulator plays an important role in detecting difficulties. This paper demonstrates the importance of the computer simulator for designing a digital controller. The controller and the simulator are constructed by different computer respectively, with a link between the blocks by analogue signals through the A/D, D/A converters. Through the simulator test, we can evaluate the digital controller; identify and solve difficulties in the digital control. The controller, which pasted the simulator test, is used identically in the actual system. This was a successful procedure for designing the controller. As an example, we successfully constructed the digital controller using the computer simulator for inverted pendulum control. We then compared the control results of simulator and actual equipment. Furthermore we commented on the construction of the computer simulator which exactly expressed the actual system.

• 영미문화
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• 제14권2호
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• pp.49-75
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• 2014

This paper argues that John Leguizamo disguises ethical intention with humor in his one-person show, Freak. The argument proceeds in three stages. First, on the basis of Slavoj ${\check{Z}}i{\check{z}}ek^{\prime}s$ theory that fantasies teach us how to desire discussed in The Sublime Object of Ideology, I analyze how and why Leguizamo exaggerates and thus de-constructs the ideological fantasies about Latin Americans in Freak. Through this analysis the ridiculous exaggeration of the fantasies and their deconstruction emerges as the means to surface the trauma caused by the fantasies, internally and externally curing and reconciling the audience. Second, I apply ${\check{Z}}i{\check{z}}ek^{\prime}s$ theory of the quilting point introduced in Looking Awry: An Introduction to Jacques Lacan through Popular Culture to reveal how "blots" in Freak form "black holes" in the audience's consciousness to smash their established view of the reality, inducing them to encounter with "the real." The investigation into Leguizamo's use of humor as the quilting point illuminates how he invites the audience to look awry beyond the popular fantasy at "the real" America. Third, on the ground of Emmanuel Levinas's theory that theaters are the space of ethics, namely "ethotopos" to emphasize responsible actions discussed in "Ethics as First Philosophy," I assert that Leguizamo disguises his ethical message with humor so as for the audience to recognize their responsibility for others in America and take action towards change.

• Geomechanics and Engineering
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• 제8권5호
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• pp.631-647
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• 2015

Engineers may encounter unpredictable cavities, sinkholes and karst conduits while tunneling in karst area, and water inrush disaster frequently occurs and endanger the construction safety, resulting in huge casualties and economic loss. Therefore, an optimal classification method based on grey system theory (GST) is established and applied to accurately predict the occurrence probability of water inrush. Considering the weights of evaluation indices, an improved formula is applied to calculate the grey relational grade. Two evaluation indices systems are proposed for risk assessment of water inrush in design stage and construction stage, respectively, and the evaluation indices are quantitatively graded according to four risk grades. To verify the accuracy and feasibility of optimal classification method, comparisons of the evaluation results derived from the aforementioned method and attribute synthetic evaluation system are made. Furthermore, evaluation of engineering practice is carried through with the Xiakou Tunnel as a case study, and the evaluation result is generally in good agreement with the field-observed result. This risk assessment methodology provides a powerful tool with which engineers can systematically evaluate the risk of water inrush in karst tunnels.