• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.141-144
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• 2008

Recently, railway has been pointed to the efficiency of transportation, rapid transit, and comfortable train ride. the construction of railway near the downtown area and station building are increasing for maximization of utilization and convenience. but the heavy of transportation and rapid transit lead to increase noise and vibration. the noise and vibration of railway may cause the civil appeal, decline in the serviceability and insufficiency of environmental standard. Therefore, the solution to avoid environmental matters becomes one of the most important factor in constructing railway. In this study, floating slab system which is one of the solution to avoid noise and vibration in railway has been introduced, and the concept of preliminary design and vibration absorber of floating slab system according to the isolator has been introduced.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.307-314
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• 2019

This paper was intended to identify the knowledge structure of youth-related research by looking at the research trends of research papers published in Korean Journal of Youth Studies from 2010 to 2018. Using keywords extracted from the papers, the Centrality and Cohesion analysis of the keyword network analysis of the NetMiner program were used. In the analysis of degree centrality, the "relationship" was the highest, followed by schools and youth, and high in the order of parents and violence. In the analysis of betweenness centrality, the "relationship" was also the highest, followed by youth, school, need, education, parents, children, abuse/emotion(the same level), institutions, regions, cell phones/prevention/welfare(the same level), elementary, attachment, suicide, addiction, society, violence, children, services, support, policy/teachers(the same level). According to the cohesion analysis, school life and policy, addiction, parent & peer relations, civic education & welfare support, sentiment and thinking, college, abuse & suicide were divided into a total of seven sub-topic subjects.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.12-21
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• 1997

Nowadays, non-pollution energy sources have been strongly needed because of the exhaustion of fossil fuels and serious environmental problems. Because wind energy can be enormously obtained from natural atmosphere, this type of energy has lots of advantages in a economic and pollution point of view. This study has established the aerodynamic and structural design procedure of the rotor blade with an appropriate aerodynamic performance and structural strength for the 500㎾ medium class wind turbine system. The aerodynamic configuration of the rotor blade was determined by considering the wind condition in the typical local operation region, and based on this configuration aerodynamic performance analysis was performed. The rotor blade has the shell-spar structure based on glass/epoxy composite material and is composed of shank including metal joint parts and blade. Structural design was done by the developed design program in this study and structural analysis, for instance stress analysis, mode analysis and fatigue life estimation, was performed by the finite element method. As a result, a medium scale wind turbine rotor blade with starting characteristics of 4m/s wind speed, rated power of 500㎾ at 12m/s wind speed and over 20 years fatigue life has been designed.

• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.25-33
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• 2004

Mobile IP Low Latency Handoffs(l) allow greater support for real-time services on a Mobile IP network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authentication the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring further involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that performs a trusted thirty party. The proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation.

• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.57-71
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• 2020

Liquefaction-induced sand boils were observed during the Pohang earthquake (Moment magnitude, 5.4) on November 15, 2017, specifically in the region of agricultural fields and park areas near the epicenter. This was recorded as the first observed liquefaction phenomenon in Korea. This paper analyzes liquefaction potentials at the key sites at Pohang area. The simplified methods and current design standard were used to evaluate the occurrence of liquefaction. The seismic demand was estimated based on the NGA-WEST2 ground motion prediction equations (GMPEs). The liquefaction resistance of the ground was determined using the in-situ tests: standard penetration test (SPT) and cone penetration test (CPT). The liquefaction potentials were quantified by liquefaction potential index (LPI), which were compared with those from the previous studies.

• Journal of the Korean GEO-environmental Society
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• v.19 no.6
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• pp.13-22
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• 2018

The southwestern part of Korean Peninsula, which length is about 13,000 km, is largely formed with soft cohesive soil ground and when it is developed, the low bearing capacity and excessive settlement of soft ground give many problems. In particular, a lot of clayey soil is deserted due to high moisture content and weakness, and areas formed with soft ground. In this study it was performed unconfined compression test, CBR tests, laboratory frost heaving test, and wheel tracking test in order to determine the optimum mixture ratio of paper sludge ash added chemical stabilizer with soft soil for consideration of its frost heaving and strength characteristics. As a results of the above experiments, when the soft soil is mixed with 6% of chemical stabilizer to improve the soft soil for utilizing as a subgrade soil material. It is satisfied the quality standard of fill materials, and the results of this research are expected to be used as an appropriate usage standard for utilization of on-site soil generated.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.55-62
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• 2009

Recently, new development projects are being carried out with the soft ground located along the West coast and the South coast. As soft grounds have complex engineering properties that the load bearing capacity is low and high compressibility, it needs to solve this problems Prior to structures are constructed by the method of improvement of soft ground. The sand mat is usually being used for improvement of soft ground as a horizontal drain material and loading base. But, as the volume is enormous and an amount of demanded sand is increased, it is state of short in supply. This paper presents the feasibility study to use of precious slag ball instead of sand mat as the replacing material through the basic soil property tests, the medium of discharge capacity test and analysis of settlement character.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.364-370
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• 2002

In this paper, we propose a VLSI array architecture for high speed processing of FBMA. First of all, the sequential FBMA is transformed into a single assignment code by using the index space expansion, and then the dependance graph is obtained from it. The two dimensional VLSI array is derived by projecting the dependance graph along the optimal direction. Since the candidate blocks in the search range are overlapped with columns as well as rows, the processing elements of the VLSI array are designed to reuse the overlapped data. As the results, the number of data inputs is reduced so that the processing performance is improved. The proposed VLSI array has (N$^2$+1)${\times}$(2p+1) processing elements and (N+2p) input ports where N is the block size and p is the maximum search range. The computation time of the rat reference block is (N$^2$+2(p+1)N+6p), and the block pipeline period is (3N+4p-1).

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.486-495
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• 2020

We surveyed disease outbreak status that has recently become a problem in organic tomatoes and cucurbit in plastic greenhouse that were grown without spraying pesticides during the plastic greenhouse growing season of 2015 to 2019. It was found that the incidence of leaf mold, tomato spotted wilt virus, and tomato chlorosis virus disease was severe in tomato, and disease incidence of powdery mildew and zucchini yellow mosaic virus were severe in Cucurbit. The disease outbreak was found to be faster and more severe in crops grown in pesticide-free cultivation plastic greenhouses than in plastic greenhouses that are cultivated in general using pesticides. In particular, the occurrence of viral diseases mediated by thrips and aphids was found to be severely damaged. Therefore, in order to produce good organic products, it is important to effectively control pests, and in order to minimize the damage caused by disease, sanitation and physical blocking, and comprehensively utilize organic materials or microorganisms to prevent them.

• Water for future
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• v.33 no.5
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• pp.61-69
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• 2000

물은 인간생활에 가장 필수적인 재화이며, 모든 산업의 기본이다. 더욱이 다른 재화와는 달리 대체재가 없다는 것에 그 심각성이 있다. 인구의 폭발적인 증가와 급격한 산업화로 지구촌의 물 부족 현상은 이미 어제 오늘의 일이 아니다. 최근 일부지역에서는 물전쟁 시나리오까지 등장하고 있다. 최근 40년간 세계의 물 소비량은 3배나 증가하였으며, 국가간 물 분쟁도 증가 추세를 보이고 있다. 우리 나라의 경우도 연평균강수량(1.27mm)이 세계평균(973mm)의 1.3배에 이르고는 있지만, 높은 인구 밀도 때문에 1인당 연간 평균강수량은 세계평균의 12.5%에 불과한 실정이다. 또한, 실질적으로 사용 가능한 자원량을 생각하면 문제는 더욱 심각하다. UN의 국제인구행동연구소(PAI:Population Action International)의 발표에 따르면, 우리 나라의 활용 가능한 자원량은 661억$m^3$으로 이를 국민 한사람당으로 환산해 보면 1.472$m^3$으로 물 부족 국가군에 해당한다. 현재 건설교통부의 수자원장기종합계획에 의하면, 우리 나라는 2006년부터 연간 4억$m^3$, 2011년부터 연간 20억$m^3$의 물이 부족할 것으로 전망하고 있다. 우리 나라 수자원 특성상 물을 확보하는데는 댐 건설 등 수자원시설이 적기에 건설되어야 하지만, 공기가 길고(10년 이상 소요), 엄청난 투자비(약 24조원), 수몰지 발생, 환경변화 등 많은 문제점들이 도출되고 있다. 그러나 미래의 물 부족에 대응하기 위해서 댐 건설(상수원전용 댐)은 불가피한 대안 중의 하나이다. 또 다른 대안으로는 교육이나 홍보를 통하여 수돗물 사용자로 하여금 자발적으로 물 사용량을 줄이도록 권고하는 방법이 있다. 또한 수도요금체계를 현실화시키거나 법규를 통하여 절수를 의무화하는 등의 방법을 통하여 물 수요를 관리하여 댐 건설이나 상수도시설 확장 등 많은 예산이 소요되는 공사를 실시하지 않고서도 급수관리와 비슷한 효과를 가질 수도 있다. 따라서 물 절약 등 수요관리를 통하여 용수수요를 줄여 나가는 방안 마련이 시급하다. 그리고 물은 한정된 자원이자 우리의 생명수이다. 이제는 수요가 증가한다고 해서 무턱대고 공급을 늘이기 위한 정책 방향으로만 갈 수는 없는 실정이다 보니 물 수요관리를 더 한층 중요하게 다루어야 할 적기가 바로 오늘이 시점부터라고 할 수 있다.