• Title/Summary/Keyword: Element analysis

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Analysis of Soil Changes in Vegetable LID Facilities (식생형 LID 시설의 내부 토양 변화 분석)

  • Lee, Seungjae;Yoon, Yeo-jin
    • Journal of Wetlands Research
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    • v.24 no.3
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    • pp.204-212
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    • 2022
  • The LID technique began to be applied in Korea after 2009, and LID facilities are installed and operated for rainwater management in business districts such as the Ministry of Environment, the Ministry of Land, Infrastructure and Transport, and LH Corporation, public institutions, commercial land, housing, parks, and schools. However, looking at domestic cases, the application cases and operation periods are insufficient compared to those outside the country, so appropriate design standards and measures for operation and maintenance are insufficient. In particular, LID facilities constructed using LID techniques need to maintain the environment inside LID facilities because hydrological and environmental effects are expressed by material circulation and energy flow. The LID facility is designed with the treatment capacity planned for the water circulation target, and the proper maintenance, vegetation, and soil conditions are periodically identified, and the efficiency is maintained as much as possible. In other words, the soil created in LID is a very important design element because LID facilities are expected to have effects such as water pollution reduction, flood reduction, water resource acquisition, and temperature reduction while increasing water storage and penetration capacity through water circulation construction. In order to maintain and manage the functions of LID facilities accurately, the current state of the facilities and the cycle of replacement and maintenance should be accurately known through various quantitative data such as soil contamination, snow removal effects, and vegetation criteria. This study was conducted to investigate the current status of LID facilities installed in Korea from 2009 to 2020, and analyze soil changes through the continuity and current status of LID facilities applied over the past 10 years after collecting soil samples from the soil layer. Through analysis of Saturn, organic matter, hardness, water contents, pH, electrical conductivity, and salt, some vegetation-type LID facilities more than 5 to 7 years after construction showed results corresponding to the lower grade of landscape design. Facilities below the lower level can be recognized as a point of time when maintenance is necessary in a state that may cause problems in soil permeability and vegetation growth. Accordingly, it was found that LID facilities should be managed through soil replacement and replacement.

Automated Analyses of Ground-Penetrating Radar Images to Determine Spatial Distribution of Buried Cultural Heritage (매장 문화재 공간 분포 결정을 위한 지하투과레이더 영상 분석 자동화 기법 탐색)

  • Kwon, Moonhee;Kim, Seung-Sep
    • Economic and Environmental Geology
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    • v.55 no.5
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    • pp.551-561
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    • 2022
  • Geophysical exploration methods are very useful for generating high-resolution images of underground structures, and such methods can be applied to investigation of buried cultural properties and for determining their exact locations. In this study, image feature extraction and image segmentation methods were applied to automatically distinguish the structures of buried relics from the high-resolution ground-penetrating radar (GPR) images obtained at the center of Silla Kingdom, Gyeongju, South Korea. The major purpose for image feature extraction analyses is identifying the circular features from building remains and the linear features from ancient roads and fences. Feature extraction is implemented by applying the Canny edge detection and Hough transform algorithms. We applied the Hough transforms to the edge image resulted from the Canny algorithm in order to determine the locations the target features. However, the Hough transform requires different parameter settings for each survey sector. As for image segmentation, we applied the connected element labeling algorithm and object-based image analysis using Orfeo Toolbox (OTB) in QGIS. The connected components labeled image shows the signals associated with the target buried relics are effectively connected and labeled. However, we often find multiple labels are assigned to a single structure on the given GPR data. Object-based image analysis was conducted by using a Large-Scale Mean-Shift (LSMS) image segmentation. In this analysis, a vector layer containing pixel values for each segmented polygon was estimated first and then used to build a train-validation dataset by assigning the polygons to one class associated with the buried relics and another class for the background field. With the Random Forest Classifier, we find that the polygons on the LSMS image segmentation layer can be successfully classified into the polygons of the buried relics and those of the background. Thus, we propose that these automatic classification methods applied to the GPR images of buried cultural heritage in this study can be useful to obtain consistent analyses results for planning excavation processes.

The Relationship between Perceived Importance of Space and Users' Satisfaction (치유의 숲 산림명상공간 인자의 중요도와 만족도)

  • Kyung-Mi Jung;Won-Sop Shin
    • Korean Journal of Environment and Ecology
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    • v.37 no.4
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    • pp.273-288
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    • 2023
  • Although many studies have been conducted on techniques and effects that can be applied to forest meditation in domestic forest healing meditation research, there has been little research on the space where forest meditation takes place. Nevertheless, a meditation space is not just a place concept but a forest environment element responsible for the healing function of a forest, i.e., a place containing healing factors, and can be an essential clue to the healing mechanism. Therefore, to determine whether a healing forest meditation space is suitable for meditation, this study selected the attribute items of the meditation space using the Delphi expert survey and then surveyed the user satisfaction of the healing forest meditation space using the IPA (Importance Performance Analysis) technique. The survey was conducted from August to November 2022, targeting 315 adults who used the forest meditation space at the National Center for Forest Therapy, the Saneum Healing Forest, and the Jathyanggi Pureunsup Arboretum in Gyeonggi Province. The result of the IPA analysis showed the average satisfaction with the forest meditation space was relatively high at 4.33 points on a 5-point Likert scale (4.33 points for the National Center for Forest Therapy, 4.34 points for the Saneum Healing Forest, and 4.37 points for the Jathyanggi Pureunsup Arboretum), indicating that the three healing forest meditation spaces were suitable for forest meditation. Satisfaction with the "Sounds of nature" was high in all three forests. On the other hand, all three forests showed a relatively low satisfaction with "Quietness," indicating it to be a priority problem to be addressed. Also, an open-ended questionnaire survey showed that the mediation space's natural elements, such as natural sounds, scenery, air, forest spaces, and scents, had a higher positive impact on meditation satisfaction than artificial elements, such as facilities. Therefore, it is essential to secure sound resources such as the sound of water and birds around the meditation space, and it is also necessary to consider ways to create a meditation forest in an independent area to avoid encounters with visitors and allow only participants in the forest healing meditation program to enter to increase satisfaction with forest meditation.

Study on Basic Elements for Smart Content through the Market Status-quo (스마트콘텐츠 현황분석을 통한 기본요소 추출)

  • Kim, Gyoung Sun;Park, Joo Young;Kim, Yi Yeon
    • Korea Science and Art Forum
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    • v.21
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    • pp.31-43
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    • 2015
  • Information and Communications Technology (ICT) is one of the technologies which represent the core value of the creative economy. It has served as a vehicle connecting the existing industry and corporate infrastructure, developing existing products and services and creating new products and services. In addition to the ICT, new devices including big data, mobile gadgets and wearable products are gaining a great attention sending an expectation for a new market-pioneering. Further, Internet of Things (IoT) is helping solidify the ICT-based social development connecting human-to-human, human-to-things and things-to-things. This means that the manufacturing-based hardware development needs to be achieved simultaneously with software development through convergence. The essential element the convergence between hardware and software is OS, for which world's leading companies such as Google and Apple have launched an intense development recognizing the importance of software. Against this backdrop, the status-quo of the software market has been examined for the study of the present report (Korea Evaluation Institute of Industrial Technology: Professional Design Technology Development Project). As a result, the software platform-based Google's android and Apple's iOS are dominant in the global market and late comers are trying to enter the market through various pathways by releasing web-based OS and similar OS to provide a new paradigm to the market. The present study is aimed at finding the way to utilize a smart content by which anyone can be a developer based on OS responding to such as social change, newly defining a smart content to be universally utilized and analyzing the market to deal with a rapid market change. The study method, scope and details are as follows: Literature investigation, Analysis on the app market according to a smart classification system, Trend analysis on the current content market, Identification of five common trends through comparison among the universal definition of smart content, the status-quo of application represented in the app market and content market situation. In conclusion, the smart content market is independent but is expected to develop in the form of a single organic body being connected each other. Therefore, the further classification system and development focus should be made in a way to see the area from multiple perspectives including a social point of view in terms of the existing technology, culture, business and consumers.

A Study on the Conservation State and Plans for Stone Cultural Properties in the Unjusa Temple, Korea (운주사 석조문화재의 보존상태와 보존방안에 대한 연구)

  • Sa-Duk, Kim;Chan-Hee, Lee;Seok-Won, Choi;Eun-Jeong, Shin
    • Korean Journal of Heritage: History & Science
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    • v.37
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    • pp.285-307
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    • 2004
  • Synthesize and examine petrological characteristic and geochemical characteristic by weathering formation of rock and progress of weathering laying stress on stone cultural properties of Unjusa temple of Chonnam Hwasun county site in this research. Examine closely weathering element that influence mechanical, chemical, mineralogical and physical weathering of rocks that accomplish stone cultural properties and these do quantification, wish to utilize by a basic knowledge for conservation scientific research of stone cultural properties by these result. Enforced component analysis of rock and mineralogical survey about 18 samples (pyroclastic tuff; 7, ash tuff; 4, granite ; 4, granitic gneiss; 3) all to search petrological characteristic and geochemical characteristic by weathering of Unjusa temple precinct stone cultural properties and recorded deterioration degree about each stone cultural properties observing naked eye. Major rock that constitution Unjusa temple one great geological features has strike of N30-40W and dip of 10-20NE being pyroclastic tuff. This pyroclastic tuff is ranging very extensively laying center on Unjusa temple and stone cultural properties of precinct is modeled by this pyroclastic tuff. Stone cultural propertieses of present Unjusa temple precinct are accomplishing structural imbalance with serious crack, and because weathering of rock with serious biological pollution is gone fairly, rubble break away and weathering and deterioration phenomenon such as fall off of a particle of mineral are appearing extremely. Also, a piece of iron and cement mortar of stone cultural properties everywhere are forming precipitate of reddish brown and light gray being oxidized. About these stone cultural properties, most stone cultural propertieses show SD(severe damage) to MD(moderate damage) as result that record Deterioration degree. X-ray diffraction analysis result samples of each rock are consisted of mineral of quartz, orthoclase,plagioclase, calcite, magnetite etc. Quartz and feldspar alterated extremely in a microscopic analysis, and biotite that show crystalline form of anhedral shows state that become chloritization that is secondary weathering mineral being weathered. Also, see that show iron precipitate of reddish brown to crack zone of tuff everywhere preview rock that weathering is gone deep. Tuffs that accomplish stone cultural properties of study area is illustrated to field of Subalkaline and Peraluminous, $SiO_2$(wt.%) extent of samples pyroclastic tuff 70.08-73.69, ash tuff extent of 70.26-78.42 show. In calculate Chemical Index of Alteration(CIA) and Weathering Potential Index(WPI) about major elements extent of CIA pyroclastic tuff 55.05-60.75, ash tuff 52.10-58.70, granite 49.49-51.06 granitic gneiss shows value of 53.25-67.14 and these have high value gneiss and tuffs. WPI previews that is see as thing which is illustrated being approximated in 0 lines and 0 lines low samples of tuffs and gneiss is receiving esaily weathering process as appear in CIA. As clay mineral of smectite, zeolite that is secondary weathering produce of rock as result that pick powdering of rock and clothing material of stone cultural properties observed by scanning electron micrographs (SEM). And roots of lichen and spore of hyphae that is weathering element are observed together. This rock deep organism being coating to add mechanical weathering process of stone cultural properties do, and is assumed that change the clay mineral is gone fairly in stone cultural properties with these. As the weathering of rocks is under a serious condition, the damage by the natural environment such as rain, wind, trees and the ground is accelerated. As a counter-measure, the first necessary thing is to build the ground environment about protecting water invasion by making the drainage and checking the surrounding environment. The second thing are building hardening and extirpation process that strengthens the rock, dealing biologically by reducing lichens, and sticking crevice part restoration using synthetic resin. Moreover, it is assumed to be desirable to build the protection facility that can block wind, sunlight, and rain which are the cause of the weathering, and that goes well with the surrounding environment.

The Research on Online Game Hedonic Experience - Focusing on Moderate Effect of Perceived Complexity - (온라인 게임에서의 쾌락적 경험에 관한 연구 - 지각된 복잡성의 조절효과를 중심으로 -)

  • Lee, Jong-Ho;Jung, Yun-Hee
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.2
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    • pp.147-187
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    • 2008
  • Online game researchers focus on the flow and factors influencing flow. Flow is conceptualized as an optimal experience state and useful explaining game experience in online. Many game studies focused on the customer loyalty and flow in playing online game, In showing specific game experience, however, it doesn't examine multidimensional experience process. Flow is not construct which show absorbing process, but construct which show absorbing result. Hence, Flow is not adequate to examine multidimensional experience of games. Online game is included in hedonic consumption. Hedonic consumption is a relatively new field of study in consumer research and it explores the consumption experience as a experiential view(Hirschman and Holbrook 1982). Hedonic consumption explores the consumption experience not as an information processing event but from a phenomenological of experiential view, which is a primarily subjective state. It includes various playful leisure activities, sensory pleasures, daydreams, esthetic enjoyment, and emotional responses. In online game experience, therefore, it is right to access through a experiential view of hedonic consumption. The objective of this paper was to make up for lacks in our understanding of online game experience by developing a framework for better insight into the hedonic experience of online game. We developed this framework by integrating and extending existing research in marketing, online game and hedonic responses. We then discussed several expectations for this framework. We concluded by discussing the results of this study, providing general recommendation and directions for future research. In hedonic response research, Lacher's research(1994)and Jongho lee and Yunhee Jung' research (2005;2006) has served as a fundamental starting point of our research. A common element in this extended research is the repeated identification of the four hedonic responses: sensory response, imaginal response, emotional response, analytic response. The validity of these four constructs finds in research of music(Lacher 1994) and movie(Jongho lee and Yunhee Jung' research 2005;2006). But, previous research on hedonic response didn't show that constructs of hedonic response have cause-effect relation. Also, although hedonic response enable to different by stimulus properties. effects of stimulus properties is not showed. To fill this gap, while largely based on Lacher(1994)' research and Jongho Lee and Yunhee Jung(2005, 2006)' research, we made several important adaptation with the primary goal of bringing the model into online game and compensating lacks of previous research. We maintained the same construct proposed by Lacher et al.(1994), with four constructs of hedonic response:sensory response, imaginal response, emotional response, analytical response. In this study, the sensory response is typified by some physical movement(Yingling 1962), the imaginal response is typified by images, memories, or situations that game evokes(Myers 1914), and the emotional response represents the feelings one experiences when playing game, such as pleasure, arousal, dominance, finally, the analytical response is that game player engaged in cognition seeking while playing game(Myers 1912). However, this paper has several important differences. We attempted to suggest multi-dimensional experience process in online game and cause-effect relation among hedonic responses. Also, We investigated moderate effects of perceived complexity. Previous studies about hedonic responses didn't show influences of stimulus properties. According to Berlyne's theory(1960, 1974) of aesthetic response, perceived complexity is a important construct because it effects pleasure. Pleasure in response to an object will increase with increased complexity, to an optimal level. After that, with increased complexity, pleasure begins with a linearly increasing line for complexity. Therefore, We expected this perceived complexity will influence hedonic response in game experience. We discussed the rationale for these suggested changes, the assumptions of the resulting framework, and developed some expectations based on its application in Online game context. In the first stage of methodology, questions were developed to measure the constructs. We constructed a survey measuring our theoretical constructs based on a combination of sources, including Yingling(1962), Hargreaves(1962), Lacher (1994), Jongho Lee and Yunhee Jung(2005, 2006), Mehrabian and Russell(1974), Pucely et al(1987). Based on comments received in the pretest, we made several revisions to arrive at our final survey. We investigated the proposed framework through a convenience sample, where participation in a self-report survey was solicited from various respondents having different knowledges. All respondents participated to different degrees, in these habitually practiced activities and received no compensation for their participation. Questionnaires were distributed to graduates and we used 381 completed questionnaires to analysis. The sample consisted of more men(n=225) than women(n=156). In measure, the study used multi-item scales based previous study. We analyze the data using structural equation modeling(LISREL-VIII; Joreskog and Sorbom 1993). First, we used the entire sample(n=381) to refine the measures and test their convergent and discriminant validity. The evidence from both the factor analysis and the analysis of reliability provides support that the scales exhibit internal consistency and construct validity. Second, we test the hypothesized structural model. And, we divided the sample into two different complexity group and analyze the hypothesized structural model of each group. The analysis suggest that hedonic response plays different roles from hypothesized in our study. The results indicate that hedonic response-sensory response, imaginal response, emotional response, analytical response- are related positively to respondents' level of game satisfaction. And game satisfaction is related to higher levels of game loyalty. Additionally, we found that perceived complexity is important to online game experience. Our results suggest that importance of each hedonic response different by perceived game complexity. Understanding the role of perceived complexity in hedonic response enables to have a better understanding of underlying mechanisms at game experience. If game has high complexity, analytical response become important response. So game producers or marketers have to consider more cognitive stimulus. Controversy, if game has low complexity, sensorial response respectively become important. Finally, we discussed several limitations of our study and suggested directions for future research. we concluded with a discussion of managerial implications. Our study provides managers with a basis for game strategies.

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Awareness Activation of Dance Copyrights and Research of Effectiveness Plans (무용의 저작권 인식 활성화와 실효성 방안 연구)

  • LEE, Seoeun
    • Trans-
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    • v.2
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    • pp.1-38
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    • 2017
  • Dance, as an art which expresses thoughts and emotions by movement human, is included in work that its copyright has to be protected, choreographers who are creators and dancers who are performing can exercise their rights included in copyright laws. However, artists who work in the dancing scene have lack of awareness about copyrights and the application level is low. The purpose of this thesis is to look into the current status and issues about dance copyright and to discuss activation plans and effectiveness plans for dance copyrights. The main point is to check into the level of awareness for dance copyrights with choreographers, dancers and students majoring in dance who are in charge of the art of dancing, to present issues about the necessity of the dance copyrights protection plans by analyzing interviews-in-depth and to prepare the dance copyrights protection plans which are concretely realistic. For the research methods, first, I looked into ideas and contents about copyrights through a document research and then, wanted to prepare theoretical background by reviewing actual cases of performing art copyrights related to dance. Next, I carried out surveys about awareness of copyrights with students majoring in dance, choreographers and dancers then carried out analysis of actual proof. Also, I chose three famous dancers who are actively performing in the current dancing scene and did interviews-in-depth about dance copyrights then carried out a recording analysis. I tried to complement the analysis by discussing deeper which I couldn't deal with in the previous surveys and to contemplate awareness activation of dance copyrights and plans. As a result of the research, the level of the awareness about dance copyrights through age, major, education and career was very low. The level of awareness was almost same compared to the previous research 10 years ago. 'Music', which can be an element of copyright issue in dance, was the highest in rate, and dance was recognized as an art which is combined with various elements as a combination work. The way of protection for works of choreography and performance only used data preservation and contracts and didn't register copyrights or record in dace notation. Majority of responders answered that they couldn't have any education about copyrights while they were recognizing the necessity of education and management for copyrights. The analysis of interviews-in-depth was also matched to the result of the previous surveys and a deeper discussion about the status of dance copyrights and issues was carried out. The plans of effectiveness for dance copyrights through the result of previous research are as followings. First, an advanced education is necessary above all to increase the awareness and application of copyrights in dancing scene. Long-term education like study curriculums and short-term education like special courses and seminars should be combined, and education about copyrights for dance groups, choreographers, dancers and students majoring in dance should keep on going. Second, revision of performing art works is necessary for the activation of dance copyrights, and establishing a dance copyright association to manage copyrights systematically and training dance copyright experts are necessary as well. Third, as the way of copyright protection for choreographers and dancers, an establishment for relation gain and loss about copyrights is necessary when creating dance works and performing, and registration of dance works should be activated. Also, the dancing scene should sign contracts for choreography and performance and this contract culture should be activated, and it should systematically preserve and manage choreography and performance records through basic ways. Hereby, it is considered to prepare a foundation to foster the awareness of dance copyrights and activate dance copyrights.

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A Methodology to Develop a Curriculum based on National Competency Standards - Focused on Methodology for Gap Analysis - (국가직무능력표준(NCS)에 근거한 조경분야 교육과정 개발 방법론 - 갭분석을 중심으로 -)

  • Byeon, Jae-Sang;Ahn, Seong-Ro;Shin, Sang-Hyun
    • Journal of the Korean Institute of Landscape Architecture
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    • v.43 no.1
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    • pp.40-53
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    • 2015
  • To train the manpower to meet the requirements of the industrial field, the introduction of the National Qualification Frameworks(hereinafter referred to as NQF) was determined in 2001 by National Competency Standards(hereinafter referred to as NCS) centrally of the Office for Government Policy Coordination. Also, for landscape architecture in the construction field, the "NCS -Landscape Architecture" pilot was developed in 2008 to be test operated for 3 years starting in 2009. Especially, as the 'realization of a competence-based society, not by educational background' was adopted as one of the major government projects in the Park Geun-Hye government(inaugurated in 2013) the NCS system was constructed on a nationwide scale as a detailed method for practicing this. However, in the case of the NCS developed by the nation, the ideal job performing abilities are specified, therefore there are weaknesses of not being able to reflect the actual operational problem differences in the student level between universities, problems of securing equipment and professors, and problems in the number of current curricula. For soft landing to practical curriculum, the process of clearly analyzing the gap between the current curriculum and the NCS must be preceded. Gap analysis is the initial stage methodology to reorganize the existing curriculum into NCS based curriculum, and based on the ability unit elements and performance standards for each NCS ability unit, the discrepancy between the existing curriculum within the department or the level of coincidence used a Likert scale of 1 to 5 to fill in and analyze. Thus, the universities wishing to operate NCS in the future measuring the level of coincidence and the gap between the current university curriculum and NCS can secure the basic tool to verify the applicability of NCS and the effectiveness of further development and operation. The advantages of reorganizing the curriculum through gap analysis are, first, that the government financial support project can be connected to provide quantitative index of the NCS adoption rate for each qualitative department, and, second, an objective standard is provided on the insufficiency or sufficiency when reorganizing to NCS based curriculum. In other words, when introducing in the subdivisions of the relevant NCS, the insufficient ability units and the ability unit elements can be extracted, and the supplementary matters for each ability unit element per existing subject can be extracted at the same time. There is an advantage providing directions for detailed class program and basic subject opening. The Ministry of Education and the Ministry of Employment and Labor must gather people from the industry to actively develop and supply the NCS standard a practical level to systematically reflect the requirements of the industrial field the educational training and qualification, and the universities wishing to apply NCS must reorganize the curriculum connecting work and qualification based on NCS. To enable this, the universities must consider the relevant industrial prospect and the relation between the faculty resources within the university and the local industry to clearly select the NCS subdivision to be applied. Afterwards, gap analysis must be used for the NCS based curriculum reorganization to establish the direction of the reorganization more objectively and rationally in order to participate in the process evaluation type qualification system efficiently.

Applicability of Partial Post-Tension Method for Deflection Control of Reinforced Concrete Slabs (RC슬래브의 처짐제어를 위한 상향긴장식 부분PT공법의 적용)

  • Lee, Deuck-Hang;Kim, Kang-Su;Kim, Sang-Sik;Kim, Yong-Nam;Lim, Joo-Hyuk
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.347-358
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    • 2009
  • Recently, it is getting into a good situation for the flat-plate slab system to be applied. The flat-plate slab without beam, however, is often too weak to control deflection properly compared to other typical slab-beam structures, for which the post-tension method is generally regarded as one of best solutions. The post-tension (PT) method can effectively control deflection without increase of slab thickness. Despite this good advantage, however, the application of PT method has been very limited due to cost increase, technical problems, and lack of experiences. Therefore, in order to reduce difficulties on applying full PT method under the current domestic circumstances and to enhance constructability of PT system, this research proposed the partial PT method with top jacking anchorage applied in a part of span as need. For the top jacking anchorage system, the efficiency of deflection control shall be considered in detail because it can vary widely depending on the location of anchorage that can be placed anywhere as need, and tensile stresses induced at back of the anchorage zone also shall be examined. Therefore, in this study, analysis were performed on the efficiency of deflection control depending on the location of anchorage and on tensile stresses or forces using finite element method and strut and tie model in the proposed top jacking anchorage system. The proposed jacking system were also applied to the floor slabs at a construction site to investigate its applicability and the analysis results of slab behavior were compared to the measured values obtained from the PT slab constructed by the partial PT method. The result of this study indicates that the partial PT method can be very efficiently applied with little cost increase to control deflection and tensile stresses in the region as a need basis where problem exists.

Petrological Characteristics and Origin of Volcaniclasts within the Massive Tuff Breccia Formation from Dokdo Island, Korea (독도 괴상 응회질 각력암층에서 나타나는 화산암편의 암석학적 특성과 기원)

  • Shim, Sung-Ho;Im, Ji-Hyeon;Jang, Yun-Deuk;Choo, Chang-Oh;Park, Byeong-Jun;Kim, Jung-Hun
    • The Journal of the Petrological Society of Korea
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    • v.19 no.2
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    • pp.141-156
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    • 2010
  • Dokdo Island, Korea, is located in the East Sea belonging to back arc basin. In this study we examined petrology and geochemistry of massive tuffaceous breccia (MTB) from Dongdo (Eastern islet) and Seodo(Western islet), the two largest islands of Dokdo. Field studies and chemical analysis distinguish the MTB in Dongdo and Seodo. The Dongdo MTB (DMTB) is exposed up to 50 m on the ocean cliff and it has dominant basalt and trachybasalt with moderate amount of trachyte and scoria. On the other hand, Seodo MTB (SMTB), which is preserved between trachyte dike and trachyandesite, is composed of roughly equal amounts of basalt, trachybasalt and trachyte. The location of the islets were related to the source vent having in contact with underlying trachyte lava and differential pyroclastic deposits made them different characteristics. According to trace element analysis of trachytic volcanic clasts, the Ba concentration ranges from 66 to 103 ppm and Sr varies from 44 to 56 ppm in DMTB. However, Br and Sr in SMTB correspondingly showed relatively wide ranges: Br 785-1259 ppm and Sr 466-1230 ppm. These differential trends between DMTB and SMTB, along with the difference in P and Ti, indicate that the crystallization of alkali feldspar, feldspathoid, biotite, apatite and titanium took place differently. Nevertheless, DMTB and SMTB are similar in REE patterns and they are correspondingly characterized by high LREE, low HREE and similar $(La/Yb)_N$ values with 23.9-40.2 in DMTB and 27.4-32.9 in SMTB. These patterns suggest that Dongdo and Seodo might be originated from coeval magma suites. Dokdo island shows high concentrations of Ba, K and Rb. These signatures mark a result attributed to the mantle upwelling because the magma derived from the asthenosphere was metasomatized with subduction-related fluids.