• Wind and Structures
• /
• v.15 no.5
• /
• pp.409-421
• /
• 2012

In this paper, the method of introducing additional source/sink terms in the turbulence and momentum transport equations was applied to appropriately model the effect of the tree canopy. At first, the new additional source term for the turbulence frequency ${\omega}$ equation in the SST k-${\omega}$ model was proposed through theoretical analogy. Then the new source/sink term model for the SST k-${\omega}$ model was numerically verified. At last, the proposed source term model was adopted in the wind environment optimal design of the twin high-rise buildings of CABR (China Academy of Building Research). Based on the numerical simulations, the technical measure to ameliorate the wind environment was proposed. Using the new inflow boundary conditions developed in the previous studies, it was concluded that the theoretically reasonable source term model of the SST k-${\omega}$ model was applicable for modeling the tree canopy flow and accurate numerical results are obtained.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.45 no.6
• /
• pp.108-116
• /
• 2008

In this paper, we propose the algorithm for making panoramic background and object tacking using pan-tilt-zoom camera. We draw an analogy relation between images for cylinder projection, rearrange of images, stitching, and blending. We can then make the panoramic background, and can track the object use the panoramic background. After generated the background, the proposed algorithm tracks the moving object. Therefore it can detect the wide area, and it tracks the object continuously. So the proposed algorithm is able to use at wide area to detect and track the object.

• Journal of The Korean Association For Science Education
• /
• v.30 no.1
• /
• pp.27-41
• /
• 2010

Scientific texts are some of major sources for scientific understanding. Therefore, reading scientific texts should be considered as an important learning activity. However, there is little research about reading scientific text in Korea. In this study, as a starting point for research about reading scientific text, lists of scientific text constituents and scientific text functions are suggested based on a comprehensive literature review. The study also reviewed how scientific text structure, familarity of scientific text and analogy involved in scientific text can affect students' scientific understanding through reading scientific text. Finally, further study plans, such as analysis of actual science textbooks using the lists suggested in this study as well as the investigation of actual students' thinking processes when reading scientific text, were described.

• The Mathematical Education
• /
• v.42 no.3
• /
• pp.353-368
• /
• 2003

Analogy, based on a similarity, is to infer the properties of the similar object from properties of an object. It can be a very useful thinking tool for learning mathematical patterns and laws, noticing on relational properties among various situations. The purpose of this study, when manipulating hint condition, figure and table conditions and the amount of original learning by using algebra word problems, is to verify the effects of analogical transfer in solving equivalent, isomorphic and similar problems according to the similarity of source problems and target ones. Five study questions were set up for the above purpose. It was 354 first grade students of S and G middle schools in Seoul that were experimented for this study. The data was processed by MANOVA analysis of statistical program, SPSS 10.0. The results of this studies would indicate that most of the students would be poor at solving isomorphic and similar problems in the performance of analogical transfer according to the similarity of source and target problems. Hints, figure and table conditions did not facilitate the analogical transfer. Merely, on the condition that amount of teaming was increased, analogical transfer of the students was facilitated. Therefore, it is necessary to have students do much more analogical problem-solving experience to improve their analogical reasoning ability through the instruction program development in the educational fields.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.6_spc
• /
• pp.705-713
• /
• 2016

Underwater noise produced by ships has been becoming an increasing issue. A dominantly contributing noise source is a ship propeller. Therefore, it is important to predict the propeller noise at the propeller design stages. This study applied the acoustic analogy based on Ffowcs Williams equation for the prediction of the marine propeller BPF noise. A marine propeller BPF noise is investigated experimentally as well as numerically. Propeller BPF noise measurement and propeller cavitation observation tests are performed in the KRISO medium size cavitation tunnel. Numerical prediction schemes of marine propeller BPF noise are presented together with the noise measurement method. Propeller BPF noise predictions and experiments are performed under the various propeller operating conditions including non-cavitating and caveating conditions. Numerical and experimental results are compared and analyzed. It is shown that numerical prediction results are generally in good agreement with the measured data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.443-449
• /
• 1996

헬리콥터, 팬, 프로펠러, 터이빈같이 회전익에서 유체역학적 소음이 발생하는 장치의 설계에 있어서는 공기 역학적 성능 분석과 함께 소음에 대한 해석이 절대적으로 필요하다. 근래에 들어와서 소음에 대한 관심이 급격히 증가하고 공항 주변에서의 국제적인 규약들은 낮은 소음 수준(low noise level)을 규정하고 있으며, 이에 따라서 소음을 감소시키려는 연구가 매우 활발히 진행되고 있는 실정이다. 더욱이 컴퓨터의 냉각 팬을 비롯한 공조기기 및 산업기기에 사용되는 회전기계에서 발생되는 소음의 저감은 보다 더 쾌적한 환경을 요구하는 사회적 요구에 부합하면서 공력소음의 연구 분야가 더 넓어지고 있다. 본 논문에서는 소음예측 방법중의 하나인 음향상사(acoustic analogy)를 주파수 영역 방법(frequency domain method)을 이용하여 헬리콥터 블레이드의 고속 충격소음(High Speed Impulsive Noise)을 해석한다. 고속 충격소음은 블레이드-와류 상호작용 소음과 더불어 헬리콥터의 지배적인 소음원으로서 깃끝 속도가 큰 전진 수평비행(forward level flight)또는 제자리 비행(hovering flight)시 발생하는 소음으로 블레이드의 깃끝 마하수(critical Mach number)보다 크거나 비슷할 경우 충격파의 교란에 의해서 일어나는 충격적인 소음을 말한다. 고속 충격소음은 고주파수 스펙트럼 성분과 큰 소음강도를 가지고 있기 때문에 날카로운 금속성의 소리를 내며 먼 거리까지 전파되는 특징을 가지고 있다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.11a
• /
• pp.69-69
• /
• 2001

We report a study of the nitriding of the martensitic grade of stainless steel AKSK 420 in a low-pressure rl discharge using pure nitrogen. Much studied samples of the austenitic grade AISI 304 were treated at the same time to provide a comparison. With a treatment time of 4.0 h at $400^{\circ}C$, the nitrogen-rich layer on MSK 420 is 20pm thick and has a hardness about 4.3 times higher than that of the untreated material. The layer thickness is much greater than that obtained on AISI 304 under identical treatment conditions, reflecting the different Cr content of the two alloys. The alloy AlISI 420 is more susceptible than AISI 304 to the formation of CrN and ferrite, and this has a deleterious effect on the hardnes, gain. Below the temperature at which CrN forms, the treated layer retains its martensitic structure, but with a larger lattice parameter than the bulk, a phase that we term expanded martensite, by analogy with the situation with austenitic stainless steel. The fact that the treated layer retains a martensitic structure is interesting in view of previous evidence that nitrogen is an austenite stabilizer.

• Journal of The Korean Association For Science Education
• /
• v.39 no.3
• /
• pp.441-456
• /
• 2019

In this study, we investigated pre-service science teachers' design for lessons using analogies in the perspectives of PCK. Three pre-service science teachers at a college of education in Seoul participated in this study. After the workshop of instructional analogies in science education, they practiced lessons using analogies in teaching practices. We observed their lessons and collected all of the teaching-learning materials. Semi-structured interviews were also conducted. The analyses of the results reveal that they dealt with mapping and unshared attribute only when using main analogies in their lessons and these processes were teacher-centered. There were some cases where they failed to adequately deal with analogies including concepts beyond the curriculum. When dealing with unshared attributes, they did not tend to accept students' opinions although they thought that unshared attributes are strongly related to misconceptions. Their understanding of assessment using analogies was not high. Assessment was relatively well done when they use student-centered analogies such as physical analogies or role-playing analogies. On the bases of the results, we suggest some educational implications for pre-service science teacher education.

• Archives of design research
• /
• v.15 no.4
• /
• pp.139-148
• /
• 2002

This study deals with the occurrence and application of 'Fun' as a linguistic function through form-giving. As a linguistic function, Fun could be defined, in a broad sense, as an emotion of desire when in relation to artifacts, and, in a narrow sense, as a physical or mental response when a person discovers unexpected information or artifacts. Hence, the occurrence of 'Fun' could be an analogy of a removal of a 'mental block' from using (or perceiving) artifacts. As an aspect of cognitive psychology, the context of form-giving, which has meanings in both artifact and design activity, will deal with an important factor of form-giving. From that, the elements of the context and the transformation of the elements are suggestive of 'Fun-oriented form-giving'. Hence, this study will show how to deal with that elements, what is required condition on it, 'Fun' in form-giving, and the Mechanism of Occurrence of 'FUN' based on this study, will be expected to apply them for product-concept effectively and Form-Giving fashionably.

• Science of Emotion and Sensibility
• /
• v.14 no.2
• /
• pp.293-300
• /
• 2011

The CGI(Computer-generated Image) techniques provide designers with an effective means of creating design artifacts in an automatic way. It has been pointed that two important activities while applying the CGI techniques are both image generation and managemental issues for the generated images. By applying automatic generation techniques for creation of images, designers can acquire benefits in that they can produce free style results in a simple way. Along with such benefits, it is also important for designer to identify and to establish well defined mechanisms for storing vast quantity of auto-generated CGIs. However, it is problematic to assign key-words and to classify abstract images mainly because they lack an analogy of the real world entities. This paper presents classification scheme for the abstract CGIs by applying classification and description criteria from the viewpoint of both design elements and emotional elements. Effective classification and specification can help designers build and retrieve desired images in an easy way, and make management process more simple and effective.