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        검색결과 55

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study measured soil respiration in pine forests dominated by Pinus densiflora in Mt. Jeombong, Mt. Namsan, Mt. Jirisan in Republic of Korea from 2009 to 2010. The seasonal variations, along with temperature and soil moisture content, were measured to understand the characteristics at each site. Soil respiration was highest in summer and autumn, closely influenced by the increase in soil temperature. Throughout the measurement period, soil respiration ranged from 205.6 to 312.2 mg CO2 m-2 h-1, with Mt. Namsan showing the highest values and Mt. Jirisan the lowest. A strong correlation was observed between soil respiration and soil temperature, with Q10 values ranging from 2.5 to 3.0. Precipitation significantly affected soil moisture content, and although it appeared to influence soil respiration, no significant correlation was found.
        4,000원
        3.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 3차원 순환 모델인 MOHID (MOdelo HIDrodinâmico) 모델을 적용하여 한반도를 포함한 동아시아 해역의 2016년 해황 변동을 재현하였다. 재현 결과는 객관 분석장(EN4, ARMOR3D, AVISO, SIO 자료)과 현장 관측 자료(정선 해양 자료, 부이 자료)를 사용하여 검증하였다. 검증 결과 MOHID로 재현된 수온, 해면 고도 편차, 표층 유속 및 혼합 층 깊이 등의 전반적인 해황 구조가 동아시아 해역의 객관 분석 자료들과 유사하게 나타났다. 특히 연안의 부이 자료와 비교하였을 때, 표층 수온 및 해면 고도 편차의 상관 계수는 모두 0.8 이상이며, 표준화된 표준편차는 0.85-1.15의 값을 보였다. 그러나 여름철 동해의 수온 약층의 구조 및 황해와 남해의 강한 성층 현상 재현에 관한 추가적인 개선이 필요할 것으로 분석되었다.
        5,800원
        4.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Block Chain is a technology that records and shares distributed ledgers without a central authority, providing a decentralized platform for transparent transactions in the business and enhancing transparency and traceability in all transactions to ensure trust in the transaction. Despite initial doubts about this technology, it is committed to adopting, adapting and improving the technology in a wide range of industries, including finance, government, security, logistics, food, medical, legal, and real estate. This study examines this technology, its applicability and potential benefits to the manufacturing supply chain. A tracking system of manufacturing supply chain to visualize transparency and traceability is implemented, and the conditions for adopting the technology in the manufacturing supply chain and the issues to be addressed are discussed.
        4,000원
        5.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the sewer pipes, reinforced concrete pipes and concrete pipes are mostly used. However, it is difficult to ensure the long-term durability of the pipe due to the corrosion of the rebar which is used for the reinforcement of the concrete. Also, reinforced concrete pipes are difficult to secure watertightness due to deterioration and corrosion by hydrogen sulfide. In order to solve such problems, research on using sewer pipes made of plastic materials is being actively conducted. When soil pressure and live load act on the buried flexible pipe, the load acting on the pipe is transferred to the surrounding soil. So, the flexible pipe will support the load with the surrounding soil together. It is difficult to predict these behaviors theoretically and clearly. Therefore, the design equation for the buried flexible pipe is analyzed by adopting theoretically idealized assumptions and it is estimated through experimental studies that it is similar to the actual structural behavior. In this paper, the mechanical properties of the soil and the polyethylene pipe were considered in application of the method proposed in ASTM D 2412 to design the buried polyethylene pipe. Also, structural behavior of the pipe resisting external loads such as soil pressure was investigated to use a polyethylene pipe as the buried pipe and the long-term behavior of the polyethylene pipe was predicted by the compaction rate of surrounding backfill soil through the field test.
        4,000원
        6.
        2017.04 구독 인증기관·개인회원 무료
        Recently, glass fiber reinforced polymer plastic (GFRP) pipes are increasing trend in using in the water-supply system because of their advantages such as light-weight, corrosion resistance, etc. GFRP pipes discussed in this paper have polymer mortar layer between filament winding glass fiber reinforced polymer plastic layers. So, GFRP pipe properties such as pipe stiffness (PS) and equivalent modulus of elasticity (Eeq ) for the design are complicated to predict or to measure. In this study, we proposed the equation that can predict the equivalent pipe stiffness factor (EI) in relation to PS and Eeq using thickness of each material layer. The predicted result obtained by the equation proposed in this paper is compared with experimental result. As a result, it was in the range of –5% to +2%. Therefore, it is found that the proposed equation can be used to design GFRP pipe used in practice.
        7.
        2017.04 구독 인증기관·개인회원 무료
        A pultruded fiber reinforced polymer plastic (PFRP) structural member consisted of plate elements, which is commonly used as construction member, may be considered as an orthotropic material due to its unique manufacturing process. It has different mechanical properties with respect to the longitudinal and transverse directions. This orthotropic nature of PFRP material needs to be considered in the analysis of buckling behavior. In this paper, a simplified buckling analysis for PFRP plate using geometric mean of the longitudinal and transverse mechanical properties is performed. The comparison between exact buckling analysis and simplified buckling analysis is conducted. Each analysis is performed by the Levy method and the finite element method (FEM), respectively.
        8.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Most of existing buried pipes are composed of reinforced concrete. Reinforced concrete pipes have many problems such as aging, corrosion, leaking, etc. The polyethylene (PE) pipes have advantages to solve these problems. The plastic pipes buried underground are classified into a flexible pipe. National standard that has limited the long-term vertical deformation of the pipe to 5% for flexible pipes including PE pipe. This study presents a prediction for the long-term behavior of the polyethylene pipe based on ASTM D 5365. This prediction method is presented to estimate by using the statistical method from the initial deflection measurement data. We predict the behavior of long-term performance on the double-wall pipe and multi-wall pipe. As a result, it was found that the PE pipe will be sound enough more than 50 years if the compaction of soil around the pipe is more than 95% of the standard soil compaction density.
        4,000원
        9.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lee, Jae Ho. 2016. “The Use of Korean Sentence-Final Endings by the Students of Chosun Hakkyo, Korean School in Japan”. The Sociolinguistic Journal of Korea 24(3). 317~343. The purpose of this paper is to present the findings which were found throughout a series of investigations performed to clarify what kind of Korean sentence-final endings the students of Korean School in Japan who are the descents of Korean immigrants use. Since the observed endings of the 1st investigation, Participant Observation, were different from the results of the 2nd investigation, Speech Task, the author interviewed the students to verify the results of the 2 investigations. Consequently, the results of Participant Observation and the interviews were generally consistent. There is, however, the possibility of students choosing and using different endings in different situations, affected by factors such as education in school and so on. The results show that the use of Korean sentence-final endings by the students is not simple.
        6,600원
        10.
        2016.06 구독 인증기관 무료, 개인회원 유료
        울진 해역 경성암반 조하대 대형무척추동물의 생물다양성을 분석하기 위하여, 2010년 3월부터 2013년 2월까지 3년간 총 5개 정점을 대상으로 계절별로 연구를 실시하였다. 이 지역에서 대형 무척추동물은 총 146종이 출현하였고, 우점 분류군은 연체동물(67종), 절지동물(27종)로, 절지동물 (6,468개체), 연체동물(1,098개체), 극피동물(584개체) 순으로 총 8,688개체가 출현하였다. 계절별 조사 시 여름철에 총 96종, 2,525개체가 출현하여 가장 높았고, 정점별 조사에서는 정점 4에서 가장 많은 출현종수에 가장 낮은 개체수를 보였으며(81종, 1,377개체수), 정점 3에서 가장 낮은 출 현종수에 가장 높은 개체수가 출현하였다(45종, 2,213개체수). 이러한 결과는 다양도와 균등도에 서는 복족류가 풍부도 측면에서는 따개비류가 큰 영향을 준 것으로 나타났으며, 정점 3에서 따개 비류가 83.4%의 비율로 다른 정점에 비해 최고 2배 이상 차이를 보여 따개비류가 서식하기 좋은 환경으로 판단되었다.
        4,000원
        11.
        2016.04 구독 인증기관·개인회원 무료
        In the water supply pipeline system, pipes made by cast iron, PE, PVC are generally used. However, the structural performance of these materials can be declined when used for long periodsof time because of corrosion, creep, deterioration of the material, etc. while glass fiber reinforced polymer plastics (GFRP) have many advantages such as light-weight, corrosion resistance, smooth surface, etc. For these reasons, GFRP pipes are good for construction when it is buried underground and are increasing trend in applying the water supply pipeline system. Therefore, more optimized structural design methodology should be developed. In this paper, we confirm pipe stiffness (PS) of GFRP pipe in which the pipe stiffness indicates the load-bearing performance. We compared data of parallel-plate loading test and theoretically predicted PS by the classical elasticity theory and the finite element method (FEM).
        12.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As the development environment is changing with the development of information communication technology, the systems that were used by each service became used with integration. In the process of integrating from existing legacy systems to new system, it should be smoothly integrated or shared, however, it cannot help holding existing technology or component due to significant cost burden for conversion. In this paper, it was not only classified by types with analyzing the various elements that make up legacy system but an approach and monitoring system were developed to each type. After System application results, data's information generated in each process is provided to other system in real time, so that it has not only secured the work efficiency and reliability but also it is made possible by integrating data in various formats for efficient data management, rapid search and tracking to history. With real-time monitoring system developed in this study, It can be very useful in a variety of industries which require real-time monitoring of distributed legacy system data.
        4,000원
        13.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Understanding of a carbon storage in a regional scale ecosystem is a very important data for predicting change of global carbon cycle. Therefore, the real data collected in the various ecosystems are a very useful for enhancing accuracy of model prediction. We tried to estimate total accumulated ecosystem carbon in Deogyusan National Park (DNP) with naturally well preserved ecosystem. In DNP, vegetations were classified to four main communities with Quercus mongolica community (12,636.9 ha, 54.8%), Quercus variabilis community (2,987.0 ha, 13.0%), Pinus densiflora community (5,758.0 ha, 25.0%), and Quercus serrata community (402.9 ha,1.7%). Biomass and soil carbons were estimated by the biomass allometric equations based on the DBH and carbon contents of litter and soil (0~30 cm) layers collected in 3 plots (30 cm×30 cm) in each community. The biomass and soil carbons were shown as high value as 1,759,000 tC and 7,776,000 tC, respectively, in Quercus mongolia community in DNP area. In Quercus mongolica, Quercus variabilis, Quercus serrata, Pinus densiflora communities, the accumulated ecosystem carbon were shown 9,536,000 tC, 1,405,000 tC, 147,000 tC, 346,000 tC, respectively. Also, the total ecosystem carbon was estimated with 11,434,000 tC in DNP.
        4,000원
        14.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Various ecosystem carry out fundamental function of material circulation and energy flow through interrelationship with many environmental factors. Therefore, it is crucial to scientifically understand the value of nature to deduce correlation between environmental factor and change of ecosystem function. In this study, we determined the accumulated ecosystem carbon and characteristics of soil respiration on grassland vegetation in Namahangang basin in Namhangang Basin. It was found that the rate of soil respiration was highly correlated with the soil temperature in all communities. The measured soil respiration rates were 1,539 mgCO2 m-2 h-1, 1,200 mgCO2 m-2 h-1, 1,215 mgCO2 m-2 h-1 in Miscanthus sacchariflorus, Phragmites japonica, Salix koreensis communities, respectively. Also, carbon quantities accumulated in litter and soil layers were 40.6 tCha-1 (1.9+38.7), 46.9 tCha-1 (43.0+3.9), 31.2 tCha-1 (28.9+2.3) in M. sacchariflorus, P. japonica, S. koreensis communities, respectively.
        4,000원
        15.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pt nanopowder-dispersed SiO2 (SOP) films were prepared by RF co-sputtering method using Pt and SiO2 targets in Ar atmosphere. The growth rate and Pt content in the film were controlled by means of manipulating the RF power of Pt target while that of SiO2 was fixed. The roughness of the film was increased with increasing the power of Pt target, which was mainly due to the increment of the size and planar density of Pt nanopowder. It was revealed that SOP film formed at 10, 15, 20 W of Pt power contained 2.3, 2.7, and 3.0 nm of spherical Pt nanopowder, respectively. Electrical conductivity of SOP films was exponentially increased with increasing Pt power as one can expect. Interestingly, conductivity of SOP films from Hall effect measurement was greater than that from DC I-V measurement, which was explained by the significant increase of electron density.
        4,000원
        16.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The evaluation of the pavement condition of the asphalt concrete pavement of No. 2 runway of Inchon International Airport through PMS, a supporting system for making a decision of pavement, maintenance and repair, was made, and the proper time for repair according to the PCI reduction rate was suggested. METHODS: By comparing and analyzing the evaluation results of pavements built in 2009, 2010, 2011, PCI change in each facility (No. 2 runway, C parallel taxiway, connection taxiway) was calculated. By applying the calculated change to PCI deduction rate model, the pavement condition of the target sections was estimated, and then the necessary section and time for repair were chosen. RESULTS: After careful consideration of the time for pavement and maintenance, based on the result of PCI prediction, it was estimated that the southern takeoff and landing section of No. 2 runway was required to be repaired in 2012; connection taxiway in 2013; and C parallel taxiway in 2014; however, the section which is the main moving route of connection taxiway and C parallel taxiway was needed to be repaired in 2012. CONCLUSIONS: For maintenance and repair of airport pavements, the optimal alternative should be chosen by considering economics and operability, via examining the time for repair and the aspect of management all together on the basis of this study.
        4,300원
        17.
        2013.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        As continued scaling becomes increasingly difficult, 3D integration has emerged as a viable solution to achieve higher bandwidths and good power efficiency. 3D integration can be defined as a technology involving the stacking of multiple processed wafers containing integrated circuits on top of each other with vertical interconnects between the wafers. This type of 3D structure can improve performance levels, enable the integration of devices with incompatible process flows, and reduce form factors. Through silicon vias (TSVs), which directly connect stacked structures die-to-die, are an enabling technology for future 3D integrated systems. TSVs filled with copper using an electro-plating method are investigated in this study. DC and pulses are used as a current source for the electro-plating process as a means of via filling. A TiN barrier and Ru seed layers are deposited by plasma-enhanced atomic layer deposition (PEALD) with thicknesses of 10 and 30 nm, respectively. All samples electroplated by the DC current showed defects, even with additives. However, the samples electroplated by the pulse current showed defect-free super-filled via structures. The optimized condition for defect-free bottom-up super-filling was established by adjusting the additive concentrations in the basic plating solution of copper sulfate. The optimized concentrations of JGB and SPS were found to be 10 and 20 ppm, respectively.
        4,000원
        18.
        2013.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 기업의 지배구조 특히, 소유구조와 사외이사의 비율에 따라 구조화 파생상품의 이용여부가 영향을 받을 것이라는 가설을 실증분석 하였다. 기존의 파생상품에 비해 구조화 파생상품은 그 헤징효과가 불명확하며 오히려 기업들을 위험에 노출시킨다는 연구들이 있는데, 이를 바탕으로 하여 본 연구는 구조화파생상품 이용에 영향을 미치는 대주주와 외국인주주 및 사외이사의 역할을 확인하고자 하였다. 표본기간은 2005년부터 2009년까지이며 12월 결산법인인 상장제조기업 중 파생상품을 이용한 기업을 대상으로 로짓분석을 실시하였다. 구조화 파생상품 이용에 대한 로짓분석 결과 소유구조, 특히 대주주지분율은 파생상품 이용에 정(+)의 관계를 보이지만 대주주지분율의 제곱은 유의한 결과값을 보이고 있지 않아서, 기존 연구와는 달리 역-U자형 관계를 보여주지는 못했다. 이와 달리 외부감시자로써의 역할을 하는 5% 이상 보유 외국인 지분율 합계와 사외이사초과선임비율은 구조화파생상품 이용에 대해 음(-)의 계수값을 보였으며, 이로부터 복잡하지만 헤지 효과가 적은 구조화 파생상품 이용이 외국인과 사외이사에 의해서는 환영받지 못하는 것으로 보인다. 또한, 외국인 지분율 합계는 통계적으로 유의한 결과를 보이지 않는데 비해 개별적으로 5%이상 보유한 외국인지분율의 합계는 음(-)의 영향을 보이고 있으며, 이로부터 기존의 외국인 투자자에 대한 연구에서와 마찬가지로 일정 지분이상을 보유한 외국인의 감시역량이 상대적으로 우월함을 알 수 있다. 전년도 파생상품이용으로 인한 이익은 다음 연도 파생금융상품 이용에 긍정적인 영향을 줄 것으로 예측되었으나 실증결과는 오히려 반대의 결과를 보였다.
        5,800원
        19.
        2013.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        육상생태계의 토양에는 대기의 약 2배에 해당하는 많 은 양의 탄소를 가지고 있으며, 기후변화에 의한 기온 상 승으로 대기로의 방출에 매우 취약한 상황에 놓여 있다. 한반도의 육상 생태계 토양탄소 수지의 변화예측을 위해 필연적으로 요구되는 다양한 생태계의 토양호흡 자료 수 집을 위해 이용되는 방법론, 기기, 기기들 간의 오차, 시 공간적인 불균일성, 결측 자료에 대한 보충 (gap filling), 발생원 별 구분 등에 대한 현 상황을 정리하고 그를 바 탕으로 국내 토양호흡 연구의 문제점과 과제에 대해 고 찰하였다. 결론적으로 국내의 토양호흡 연구는 기기 간 또는 방법들 간의 오차 보정이나 노력들이 매우 빈약하 게 행해져 왔기 때문에 과거 및 현재 축적되는 자료의 품질은 거의 보정되지 않은 상태로 볼 수 있다. 이러한 문제점들이 해소되지 않고 지금까지와 같은 방식으로 토 양호흡 자료가 축적된다면 그 활용성은 매우 낮을 수 밖에 없다. 또한 장기적인 자료 축적, 토양호흡 조절 메커니 즘에 관한 조절 실험, 다양한 생태계, 토성, 토심 등에 대 한 자료 역시 장래의 토양권 탄소 동태 변화를 모델 수 단으로 예측하는 데에는 매우 중요한 요소이므로 토양호 흡 자료 수집과 함께 수집되어야 할 것이다. 더불어 장기 적인 측면에서 이러한 문제들이 연구자 간에 깊숙이 인 식되어 보다 양질의 자료가 생산되도록 노력할 필요가 있다.
        4,000원
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