• Title/Summary/Keyword: multi-layered approach

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Autofrettage Analysis of Compound Cylinder with Power Function Strain Hardening Model (멱함수 가공경화 모델을 이용한 복합실린더의 자긴가공해석)

  • Park, Jae-Hyun;Lee, Young-Shin;Shim, Woo-Sung;Kim, Jae-Hoon;Cha, Ki-Up;Hong, Suk-Kyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.6
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    • pp.488-495
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    • 2008
  • In order to achieve long fatigue lifetimes for cyclically pressurized thick cylinders, multi-layered compound cylinder has been proposed. Such compound cylinder involves a shrink-fit procedure incorporating a monobloc tube which has previously undergone autofrettage. The basic autofrettage theory assumes elastic-perfectly plastic behaviour. Because of the Bauschinger effect and strain-hardening, most materials do not display elastic-perfectly plastic properties and consequently various autofrettage mo dels are based on different simplified material strain-hardening models, which is assumed that combination of linear strain-hardenig and power strain-hardening model. This approach gives a more accurate prediction than the elastic-perfectly plastic model and is suitable for different strain-hardening materials. In this paper, a general autofrettage model that incorporates the material strain-hardening relationship and the Bauschinger effect, based upon the actual tensile-compressive stress-strain curve of a material was proposed. The model was obtained using the von Mises yield criterion and plane strain condition. The tensile-compressive stress-strain curve was obtained by experiment. The parameters needed in the model were determined by fitting the actual tensile-compressive curve of the material. Finally, strain- hardening model was compared with elastic-perfectly plastic model.

A Study on Effectiveness Analysis of K2 system with Weapon's unit cost (무기체계 단위비용을 고려한 K2 체계의 효과분석 방법 연구)

  • Jung, Byungki
    • Journal of the Korea Society for Simulation
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    • v.26 no.2
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    • pp.31-39
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    • 2017
  • This paper analyses the effectiveness of Kill Chain (KC) and Korea Air and Missile Defense (KAMD), also known as the K2 systems, using monte carlo simulation. It is assumed that the K2 systems are consisted with unitary KC and multi-layered (upper-tier and lower-tier) KAMD. And each system has two or three arbitrary weapon systems and its combination makes 12 scenarios. Measures of effectiveness (MOE) of the K2 systems were defined as ratio of eliminated ballistic missiles from total threats. And total cost was calculated by number of weapon launched and its unit cost. MOE and total cost of the K2 systems were estimated using monte carlo simulation with a thousand iteration for each scenario. Cost-effectiveness analysis was performed and the best candidate was selected using fixed effectiveness approach. As a result, the performances of KC are prime factor that affects both effectiveness and total cost of the K2 systems. It is also, acquired proper level of lower-tier KAMD to achieve desired defense effectiveness. For future work, it needs to be performed cost-effectiveness analysis based on practical specification and life cycle cost of weapon systems.

A Study on the Territoriality and the Socio-spatial Characteristics of a Commoner's Settlement in Modern Times (${\cdot}$현대 민촌의 사회공간적 성격과 영역성 - 부여군 장암면 장하리의 사례 -)

  • Jeon Jong-Han
    • Journal of the Korean Geographical Society
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    • v.40 no.6 s.111
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    • pp.613-630
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    • 2005
  • In this article, the author inquired the multi-layered sphere of a commoner's settlement of Jangha-ri in modem times to approach the territoriality and socio-spatial characteristics of it. This settlement has originated in a lineage settlement of Jinju-Gang, and has experienced socio-spatial cohesion since its making(the 17th Century). Especially, it is found that the territoriality of Jangha-ri has fluctuated in times and has obtained multi-layeredness according to the human-nature relationship, to the social relationship, and to the political relationship of villagers. As a result, it is interpreted that the socio-spatial characteristics and territoriality of Jangha-ri in modem times do not only have a physical reality, but also social, political, cultural one.

Classification of Natural and Artificial Forests from KOMPSAT-3/3A/5 Images Using Deep Neural Network (심층신경망을 이용한 KOMPSAT-3/3A/5 영상으로부터 자연림과 인공림의 분류)

  • Baek, Won-Kyung;Lee, Yong-Suk;Park, Sung-Hwan;Jung, Hyung-Sup
    • Korean Journal of Remote Sensing
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    • v.37 no.6_3
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    • pp.1965-1974
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    • 2021
  • Satellite remote sensing approach can be actively used for forest monitoring. Especially, it is much meaningful to utilize Korea multi-purpose satellites, an independently operated satellite in Korea, for forest monitoring of Korea, Recently, several studies have been performed to exploit meaningful information from satellite remote sensed data via machine learning approaches. The forest information produced through machine learning approaches can be used to support the efficiency of traditional forest monitoring methods, such as in-situ survey or qualitative analysis of aerial image. The performance of machine learning approaches is greatly depending on the characteristics of study area and data. Thus, it is very important to survey the best model among the various machine learning models. In this study, the performance of deep neural network to classify artificial or natural forests was analyzed in Samcheok, Korea. As a result, the pixel accuracy was about 0.857. F1 scores for natural and artificial forests were about 0.917 and 0.433 respectively. The F1 score of artificial forest was low. However, we can find that the artificial and natural forest classification performance improvement of about 0.06 and 0.10 in F1 scores, compared to the results from single layered sigmoid artificial neural network. Based on these results, it is necessary to find a more appropriate model for the forest type classification by applying additional models based on a convolutional neural network.

An Longitudinal Analysis of Changing Beliefs on the Use in IT Educatee by Elaboration Likelihood Model (정교화 가능성 모형에 의한 IT 피교육자 신용 믿음 변화의 종단분석)

  • Lee, Woong-Kyu
    • Asia pacific journal of information systems
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    • v.18 no.3
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    • pp.147-165
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    • 2008
  • IT education can be summarized as persuading the educatee to accept IT. The persuasion is made by delivering the messages for how-to-use and where-to-use to the educatee, which leads formulation of a belief structure for using IT. Therefore, message based persuasion theory, as well as IT acceptance theories such as technology acceptance model(TAM), would play a very important role for explaining IT education. According to elaboration likelihood model(ELM) that has been considered as one of the most influential persuasion theories, people change attitude or perception by two routes, central route and peripheral route. In central route, people would think critically about issue-related arguments in an informational message. In peripheral route, subjects rely on cues regarding the target behavior with less cognitive efforts. Moreover, such persuasion process is not a one-shot program but continuous repetition with feedbacks, which leads to changing a belief structure for using IT. An educatee would get more knowledge and experiences of using IT as following an education program, and be more dependent on a central route than a peripheral route. Such change would reformulate a belief structure which is different from the intial one. The objectives of this study are the following two: First, an identification of the relationship between ELM and belief structures for using IT. Especially, we analyze the effects of message interpretation through both of central and peripheral routes on perceived usefulness which is an important explaining variable in TAM and perceived use control which have perceived ease of use and perceived controllability as sub-dimensions. Second, a longitudinal analysis of the above effects. In other words, change of the relationship between interpretation of message delivered by IT education and beliefs of IT using is analyzed longitudinally. For achievement of our objectives, we suggest a research model, which is constructed as three-layered. While first layer has a dependent variable, use intention, second one has perceived usefulness and perceived use control that has two sub-concepts, perceived ease of use and perceived controllability. Finally, third one is related with two routes in ELM, source credibility and argument quality which are operationalization of peripheral route and central route respectively. By these variables, we suggest five hypotheses. In addition to relationship among variables, we suggest two additional hypotheses, moderation effects of time in the relationships between perceived usefulness and two routes. That is, source credibility's influence on perceived usefulness is decreased as time flows, and argument quality's influence is increased. For validation of it, our research model is tested empirically. With measurements which have been validated in the other studies, we survey students in an Excel class two times for longitudinal analysis. Data Analysis is done by partial least square(PLS), which is known as an appropriate approach for multi-group comparison analysis with a small sized sample as like this study. In result. all hypotheses are statistically supported. One of theoretical contributions in this study is an analysis of IT education based on ELM and TAM which are considered as important theories in psychology and IS theories respectively. A longitudinal analysis by comparison between two surveys based on PLS is also considered as a methodological contribution. In practice, finding the importance of peripheral route in early stage of IT education should be notable.

A Neural Network for Long-Term Forecast of Regional Precipitation (지역별 중장기 강수량 예측을 위한 신경망 기법)

  • Kim, Ho-Joon;Paek, Hee-Jeong;Kwon, Won-Tae
    • Journal of the Korean Association of Geographic Information Studies
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    • v.2 no.2
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    • pp.69-78
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    • 1999
  • In this paper, a neural network approach to forecast Korean regional precipitation is presented. We first analyze the characteristics of the conventional models for time series prediction, and then propose a new model and its learning method for the precipitation forecast. The proposed model is a layered network in which the outputs of a layer are buffered within a given period time and then fed fully connected to the upper layer. This study adopted the dual connections between two layers for the model. The network behavior and learning algorithm for the model are also described. The dual connection structure plays the role of the bias of the ordinary Multi-Layer Perceptron(MLP), and reflects the relationships among the features effectively. From these advantageous features, the model provides the learning efficiency in comparison with the FIR network, which is the most popular model for time series prediction. We have applied the model to the monthly and seasonal forecast of precipitation. The precipitation data and SST(Sea Surface Temperature) data for several decades are used as the learning pattern for the neural network predictor. The experimental results have shown the validity of the proposed model.

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Effects of Ambient Temperature Change on the Internal Pressure Change of Multi-Layered Subsea Pipeline (주위 온도변화가 다층구조 해저 파이프라인 내부 압력변화에 미치는 영향)

  • Yang, Seung Ho
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.772-779
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    • 2019
  • The subsea pipeline has received considerable attention as a high-value-added industry linked to the energy and steel industries including natural resource development. The design and installation of the subsea pipeline require a variety of key technologies to carry out the project. In particular, a thorough pre-verification process through pre-commissioning is essential for the safe operation of the subsea pipeline. The hydrotesting stage in the pre-commissioning process of the subsea pipeline is known to be affected significantly by the ambient temperature change; however, there is a little study based on the theoretical and numerical approach. In this study, the method of predicting the internal temperature change using the transient heat transfer method for the stage of hydrotesting during the pre-commissioning process of the subsea pipeline and the prediction method of the pressure variation in the pipeline using it were proposed. The predicted results were compared with field test results and its effectiveness was verified. The proposed analysis procedure is expected to contribute to the productivity improvement of the subsea pipeline installation project by enabling the prediction of pressure variation through pipeline heat transfer simulation from the initial design stage of the subsea pipeline installation project.

Understanding and Applicability of Identity-in-practice Theory (실행 과정에서의 정체성 이론의 이해와 적용 방안)

  • Kim, Jong-Uk;Kim, Chan-Jong
    • Journal of The Korean Association For Science Education
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    • v.41 no.3
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    • pp.267-281
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    • 2021
  • The shift in the perspective on learning as participation draws attention to learners' identity work. This manuscript foregrounds the ongoing and fluid processes of identity, and focuses on the structure surrounding learners where identity work occurs and the expression of individual agency. From the perspective of learning as participation, we introduce Holland et al. (1998) identity-in-practice theory, as the theoretical lens that dialectically describes structure, agency and identity. The concepts representing this theory are 'figured world', 'positionality' and 'authoring self'. The figured world is a web of meaning encompassing the continuous construct/reconstruct through human actions and also exerts as the social force that shapes human actions. 'Positionality' on the other hand, means an understanding of one's social position in the world. The notion of 'authoring self', is a dimension that synthesizes the above two concepts, which describes the improvisation of one's self through the orchestration and collaboration of various social voices. Next, we analyzed and described various cases of this theory that we found within the scope of science education. However, due to the nature of this theory, which takes a sociocultural approach, international research studies cannot be simply applied to the Korean context. Therefore, we sought to expand the applicability of this theory as a methodological tool, by discussing the directions in which this theory can be used in a domestic context. It is intended that the introduction of this theory, which emphasizes multi-layered, continuous and cumulative identity work, will be used as a resource to further expand the horizon of science education reform that is required for the times.

Reading the Landscape through the Perception of Residents of Banwol and Bakji Island - Based on the Change before and after the Purple Island - (반월·박지도 주민의 인식과 태도를 통해 경관 읽기 - 퍼플섬(Purple Islands) 사업 전후의 변화를 중심으로 -)

  • Hamm, Yeonsu;Seo, Hwahyun;Cui, Yuna;Sung, Jong-Sang
    • Journal of the Korean Institute of Landscape Architecture
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    • v.51 no.4
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    • pp.56-75
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    • 2023
  • As of 2019, for the 'Island I Want to Visit' project, Banwol and Bakji Islands, located in Shinan-gun, started color marketing to create a tourist attraction by painting roofs, buildings, and facilities purple. As this landscape change was evaluated as a 'dangerous but beautiful attempt,' it was recognized as the 'World's Best Tourism Village' in 2021, drawing attention from domestic and foreign tourists. However, the residents of the islands, who created and enjoy the benefits of the landscape, were alienated from the planning stage. This study investigated the meanings and symbols of residents' perceptions of the purple landscape. The cultural landscape frame of new cultural geography, which interprets the landscape's symbolic meaning and ideological signs, was utilized. In addition, a holistic approach was applied to understand the residents' perceptions of the multi-layered environment. Therefore, the perception of purple, the main color of the islands, the overall landscape and individual places, and the general perception of the Purple Island project were investigated. After the Purple Islands Project, the main senses for recognizing the villages focused on sight, and the residents were satisfied with the purple landscape as it improved the underdeveloped village environment. This satisfaction was based on lessening the negative memories experienced as an island rather than a value judgment on the purple color. In addition, the perception of the symbolic landscape, which has a social and universal system, has been subdivided and reorganized, including for tourism functions. It can be understood as an aspect of the spectacle landscape that appears in cosmopolitanism. However, in the process of transforming into a tourist attraction, it was discovered that the residents recognize the value of local resources and create a new cultural landscape. In addition, the perception of the relationship between Banwol and Bakji has also changed around tourism.

A Study on the Continuous Utilization of Japan's Cultural Heritage Through the Cases of Silk Heritage, World Heritage, and the Japan Heritage Project in Gunma Prefecture (일본 문화유산의 연속적 활용에 관한 연구 - '군마 실크유산'과 세계유산, 일본유산 사업을 중심으로 -)

  • Lee, Chungsun
    • Korean Journal of Heritage: History & Science
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    • v.52 no.1
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    • pp.190-211
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    • 2019
  • In March 2015, The Agency for Cultural Affairs of Japan implemented a project called "Japan Heritage," which aims to promote the unique narratives of cultural properties of the region by branding the locality for revitalization in preparation for the 2020 Tokyo Olympics and Paralympics. This bottom-up approach of cultural policy has been called a "Cool Japan Strategy of Cultural Heritage" in the 21st century, which effectively incorporates local cultural heritage and tourism. However, although a total of 67 Japan Heritage projects have been designated as of December 2018, almost none has been introduced in the academic forum in Korea. On the basis of this background and a lack of academic awareness in Korea on Japan's recent cultural policies, this research aims to focus on the three cases of Gunma Prefecture implemented in local, global, and glocal aspects. To specify, the cases are the "Gunma Silk Heritage" project, implemented in 2011, the "Tomioka Silk Mill and Related Sites" project that was included on the UNESCO World Heritage List in 2014, and "The Best Wife in the World - Silk Story of Gunma," case certified as the first project of "Japan Heritage" launched in 2015. Based on the questionnaire method conducted with the World Heritage Registration Promotion Division in Gunma Prefectural Government, as well as a literature view, the research revealed that the consecutive implementation of a series of cultural heritage projects in Gunma is not coincidental, but rather a strategy aiming to create a synergism where each project complements the others. Moreover, this paper demonstrates that Gunma Prefecture has been utilizing the local silk industry as a tangible and intangible cultural resource in multi-layered heritage projects, resulting in a "spiral synergy effect" and a "chain of the recognition process." In conclusion, it illustrates the recent trend of utilizing cultural heritage in the context of the Cool Japan strategy, which seeks to move away from the administration of maintaining the status quo cultural heritage protection to a proactive one with greater potential growth. This research may thus provide meaningful insight into the utilization of domestic historical and cultural resources as well as related policy-making, in that it will ultimately promote the chain effect of linking the multiple heritage policies and projects at the local, global, and glocal levels.