• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.101-106
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• 1999

Open dump of refuse causes groundwater and soil contamination by leachate and air pollution by LFG(Landfill Gas). In this paper, in order to perform a study about reduction of high leachate and LFG collection & control, using a 3-D, 2-phase, transient FDM model, the analysis of simultaneous flow of leachate and LFG has been carried out. In present numerical analysis it is assumed that 58 percents of LFG will evaporate to the ambient air and the recharge rate of a landfill be 12 percent of the average precipitation per year. All other data were excerpted at the point of 1995 when three refuse layers had been buried. From numerical analysis we concluded that maximum head value is approximately 26 mH2O<-에이치투오 (2.52 atm) in the center of the system and that installing venting trench plays an important role in landfill stabilization. Evan with the assumption of three layers constructed and low recharge rate applied, it is found that cumulative leachate and LFG productions will be 15.1 million 세제곱미터, 5.58 billion 세제곱미터, respectively after 40 years.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.797-804
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• 2013

In this study, the authors develop a methodology for a diagnostic system with a vibration parameter that is influenced by environmental factors. The data tends to have a varying average over time. Often, these features are found in statistical data retrieved from a production line. If we utilize existing statistical techniques for these features, we could derive an incorrect diagnostic conclusion based on the different average values. To overcome the limitations of previous methods, the authors apply a function analyzed through regression analysis to predict the mean value and corresponding upper and lower limits at each stage. This technique also provides corresponding statistical parameters in varying dynamic means. To validate the proposed methods, we retrieve data from the engine assembly line of H Motors and verify the results.

• Information and Communications Magazine
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• v.28 no.1
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• pp.22-28
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• 2010

외환위기 이후 IT는 우리 경제의 견인차로 인식되어 왔으나 2000년대 초두의 IT 버블 붕괴 이후 극심한 성장정체를 겪으면서 일부 학자 및 정책입안자를 중심으로 IT 역할에 대한 회의론적 시각이 제기되어 왔다. 그러나, 지난 2~3년간의 각종 경제지표를 볼 때, IT는 여전히 우리 경제에서 중요한 역할을 하고 있음을 확인할 수 있을 뿐만 아니라 미래사회에의 대응을 위해서도 IT에 대한 관심 제고가 무엇보다도 절실한 시점이라 하겠다. 특히, 스마트폰의 등장에 따라 스마트폰 환경에 최적화된 다양한 애플리케이션의 등장과 이를 이용한 모바일 서비스의 보급 확산으로 IT 기기 및 서비스 산업의 경쟁구조에 근본적인 변화가 발생하면서 IT 강국이라는 국가적 브랜드마저 위협받고 있는 시점이어서 더욱 그렇다. 스마트폰의 등장으로 국가경쟁력 결정 패턴이 노동과 자본 등 전통적인 생산요소에 기반한 개별 산업분야의 경쟁우위를 기초로 결정되던 형태에서 감성과 창의성 등 소프트 파워의 보유 정도에 따라 결정되는 형태로 전환되었다는 점에서 R&D전략에 있어서도 중요한 전환점을 맞고 있다고 보여진다. 또한, 산업사회와 정보사회에 이어 급격한 기술혁신에 따른 기술간 및 산업간 융합의 정도가 산업 전반의 경쟁구도에 영향을 미칠 것으로 대부분의 전문가들이 예견하고 있으나, 산업현장이나 기술분야에서 실제적으로 발생되는 융합의 양상은 그다지 신속하지 못한 것으로 나타나고 있다. 따라서, 기술간 및 산업간 융합촉진을 통한 전산업 경쟁력 제고를 위한 R&D 방향 모색이 필요한 시점이다. 이에 따라 본고에서는 스마트폰의 등장에 따른 IT산업의 경쟁구도 변화와 글로벌 기업들의 전략, 대응방향 등을 살펴보는 한편 IT의 전반적인 활용도 증가에 따라 더욱 가속화될 것으로 전망되는 기술간 및 산업간 융합시대에 대응한 IT R&D 방향을 살펴본다. 이는 궁극적으로 IT 강국이라는 국가적 브랜드 이미지의 고착화 전략인 동시에 IT 기반의 융합을 촉진시킴으로써 스마트한 IT Korea라는 국가적 미래비전을 달성해 나가기 위한 방향이 될 것이다.

• Information Systems Review
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• v.24 no.4
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• pp.41-54
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• 2022

Despite the recent rapid advancement of science and technology, we have been experiencing the decline in productivity since the 2000s. This study aims to investigate the decline at both industry and firm levels, by looking at the emergence and growth of large firms such as Amazon, Alphabet, and Apple and M&A trends. Following the results of previous studies, our results show that productivity at industry level has decreased since the 2000s. Particularly, in the period after 2011, the deterioration of allocative efficiency due to the large firms and the decline in the growth rate of surviving firms in the industry with low ratio of large firms contributed to the productivity decline. On the other hand, our analysis at firm level demonstrates that the productivity of firms that acquired IT firms improved over the entire period. While M&As have a positive impact on productivity, M&As with a demand-side motive such as market penetration and expansion of channels have a relatively larger impact than the ones for production or operation efficiency. Our results also suggest that the higher the proportion of large firms in a specific industry, the lower the productivity of individual firms in the same industry. Overall, given that the industry's structural changes for digital transformation tends to strengthen the growth of large firms, our findings have significant implications by empirically identifying the relationships of the emergence of large firms, the acquisition of IT/Non-IT firms, and motivations for M&As to firm/industry productivity.

• New & Renewable Energy
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• v.3 no.2 s.10
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• pp.31-39
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• 2007

화석연료의 사용으로 인한 자원고갈과 지구온난화 영향 그리고 에너지 안보문제의 해결을 위해 세계 각국들은 대체에너지 개발에 많은 노력을 기울이고 있다. 그 중 수소는 다양한 경로를 통해 생산 가능하고, 수송연료로 사용 시, 유해 물질이 거의 배출되지 않는다는 장점 때문에 가장 주목받는 대체 에너지원이다. 현재는 수소생산 기술개발을 통해 상업화시기를 앞당기려고 하는 수소에너지 시대의 진입시점이라 할 수 있다. 그러나 수소는 생산경로에 따라 다양한 환경성 및 경제성 결과를 도출 할 수 있기 때문에 다양한 평가가 요구된다. 본 연구에서는 국내 수소생산 방식으로 개발/상용화되어있는 Natural Gas Steam Reforming (NGSR), Naphtha Steam Reforming (Naphtha SR), Water Electrolysis (WE)에 대하여, Life Cycle Assessment (LCA)와 Life Cycle Costing Analysis (LCCA) 방법을 사용하여, 수소경로 전반에 대한 즉, 원료채취부터 자동차로 주행하였을 때까지의 각 대상 수소경로의 환경성과 경제성을 평가하였다. LCA와 LCCA 결과는 Naphtha SR과 NGSR 수소경로에서 지구온난화와 화석자원 소모 부문 모두 기존연료 (가솔린, 디젤)와 비교해서 개선효과가 뚜렷하게 나타났으나, WE 수소경로는 오히려 환경부하가 증가되는 것으로 나타났다. 또한 경제성 측면에서는, 수소 판매 시 가솔린과 동일한 연료세율을 부과하더라도 수소가 가솔린에 비해 가격경쟁력을 확보하게 되는데, 이는 주행 시 수소자동차의 연비가 기존 차량에 비해 월등히 좋기 때문에 연료비용의 이점 때문이다. 만약, 수소에 연료세를 부과하지 않는 다면, Naphtha SR로 생산하여 유통한 수소가 수송연료로서 가장 뛰어난 비용효율성을 갖는 것으로 나타났다.

• Journal of Practical Engineering Education
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• v.16 no.1_spc
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• pp.1-9
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• 2024

The introduction of smart factory digital twins is a concept that has already been proposed to increase productivity in the manufacturing industry through CPS(Cyber Physics System), and has been applied to specific industrial process stages or partially introduced in stages where simulation is required. However, with the recent development of the 4th Industrial Revolution technology, it is receiving attention again along with XR (Extended Reality) technology. However, because there are not many effective cases, this study analyzed the devices, equipment, and technology of the manufacturing process to build a digital twin applying digital threads and synchronized signals and information to control, remote control, and produce intelligent process automation equipment. A platform capable of analyzing information was proposed and developed. Through this, we designed and built an XR content service platform that can support artificial intelligence and developed it to enable control, remote control, and analysis of production information. A possible platform was proposed and developed. We hope that this study will be helpful in conducting research on many cases, and in the future, expanded research on increasing productivity in each part of the process and production is needed through intelligent models.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.388-398
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• 2020

Watermelon yield mainly depends on soil water content controlled by irrigation in a plastic greenhouse. In this study, we investigated the effect of different soil moisture contents affected by irrigation starting point on growth, yield, and physiological responses of small-sized watermelons. Irrigation was initiated at 5 different levels of soil water content as a starting point with soil moisture detecting sensor after 14 days of transplanting, and stopped at 7 ~ 10 days before harvest. These treatments were compared with the conventional periodic irrigation as control. When soil had the lowest moisture content (-50 kPa), the overall shoot growth was retarded, but the root length and root dry weight increased. The photosynthetic parameters (photosynthetic rate, stomatal conductance, and transpiration rate) of watermelon leaves decreased significantly in the lowest soil moisture content (-50 kPa). On the other hand, the photosynthetic rates of watermelon leaves grown with irrigation starting point between -20 and -40 kPa were observed to be higher than those of other treatments. Fruit set rate and marketable fruit yield increased significantly at -30 kPa and -40 kPa. Proline, abscisic acid (ABA), total phenol and citrulline, which are known to contribute to stress tolerance under drought condition, increased as soil water content decreased, particularly, the largest increases were recorded at -50 kPa. From these results, it was found that an appropriate water supply adjusted with an irrigation starting point between -30 and -40 kPa could help to keep favorable soil water content during the cultivation of small-sized watermelons, promoting the marketable fruit production as well as inducing the vigorous plant growth and reproductive development.

• Journal of Korea Water Resources Association
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• v.49 no.1
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• pp.19-28
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• 2016

The objective of this study is the generation of the gridded flash flood index using the gridded hydrologic components of TOPLATS land surface model and statistic flash flood index model. The accuracy of this method is also examined in this study. The study area is the national capital region of Korea, and 38 flash flood damages had occurred from 2009 to 2012. The spatio-temporal resolutions of land surface model are 1 h and 1 km, respectively. The gridded meteorological data are generated using the inverse distance weight method with automatic weather stations (AWSs) of Korea Meteorological Administration (KMA). The hydrological components (e.g., surface runoff, soil water contents, and water table depth) of cells corresponding to the positions of 38 flood damages reasonably respond to the cell based hourly rainfalls. Under the total rainfall condition, the gridded flash flood index shows 71% to 87% from 4 h to 6 h in the lead time based on the rescue request time and 42% to 52% of accuracy at 0 h which means that the time period of the lead time is in a limited rescue request time. From these results, it is known that the gridded flash flood index using the cell based hydrological components from land surface model and the statistic flash flood index model have a capability to predict flash flood in the mountainous area.

• The Korean Journal of Archival Studies
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• no.16
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• pp.97-146
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• 2007

Those days when people used paper to make up and manage all kinds of documents in the process of their jobs are gone now. Today electronic types of documents have replaced paper. Unlike paper documents, electronic ones contribute to the maximum job efficiency with their convenience in production and storage. But they too have some disadvantages; it's difficult to distinguish originals and copies like paper documents; it's not easy to examine if there is a change or damage to the documents; they are also prone to alteration and damage by the external influences in the electronic environment; and electronic documents require enormous amounts of workforce and costs for immediate measures to be taken according to the changes to the S/W and H/W environment. Despite all those weaknesses, however, electronic documents increasingly account for more percentage in the current job environment thanks to their job convenience and efficiency of production costs. Both the government and private sector have made efforts to come up with plans to maximize their advantages and minimize their risks at the same time. One of the methods is the Authorized Retention Center which is described in the study. There are a couple of prerequisites for its smooth operation; they should guarantee the legal validity of electronic documents in the administrative aspects and first secure the reliability and authenticity of electronic documents in the technological aspects. Responding to those needs, the Ministry of Commerce, Industry and Energy and the Korea Institute for Electronic Commerce, which were the two main bodies to drive the Authorized Retention Center project, revised the Electronic Commerce Act and supplemented the provisions to guarantee the legal validity of electronic documents in 2005 and conducted researches on the ways to preserve electronic documents for a long term and secure their reliability, which had been demanded by the users of the center, in 2006. In an attempt to fulfill those goals of the Authorized Retention Center, this study researched technical standard for electronic record information package of the center and applied the ISO 14721 information package model that's the standard for the long-term preservation of digital data. It also suggested a process to produce and manage information package so that there would be the SIP, AIP and DIP metadata features for the production, preservation, and utilization by users points of electronic documents and they could be implemented according to the center's policies. Based on the previous study, the study introduced the flow charts among the production and progress process, application methods and packages of technical standard for electronic record information package at the center and suggested some issues that should be consistently researched in the field of records management based on the results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.645-653
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• 2012

The productivity management of highway construction is required to innovate the efficiency of investment The productivity management of highway construction is required to innovate the efficiency of investment cost for newly constructed projects and to improve the quality of these projects, as the maintenance and management expenses are steadily increasing for existing highways under operation. However, clear criteria, methods or requirements to measure the productivity and performance in the construction of highways have not been properly established yet. This study defined 5 major elements of the productive projects in terms of construction management which is one of major tasks of the owner. There were the 43 influential elements significantly affecting on the productivity and these elements were categorized into the hierarchical structure which was composed of 3 levels. Also, this study conducted a survey for Korea Expressway Corporation who is the largest owner in Korea's highway construction. As a result, major project performance indicators, which should be addressed for management, to execute the projects successfully, are presented through understanding the extent of the affection of productivity elements on the elements of project performance to attain the productive projects and through understanding the extent of demand to be improved.