• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.421-426
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• 2003

Recently, mixers are being widely used in the water purification plant in order to increase the filtration efficiency. The mixer normally consists of impeller, shaft, hub, reduction gear, and the driving motor. It is one of the key design issues to confirm that the vibration caused by the rotation of the shaft should not coincide with the natural vibration frequency of the shaft itself. The vibration characteristics of the hydrofoil type mixer, which is the most widely used in real plants are evaluated through the finite element modeling and verified by experiment using the mock-up facility. The fundamental natural frequency of the mixer's shaft is found to be around 1.8 Hz which showed in good agreement with the experiment. The higher natural frequencies to the 2nd, 3rd, and 4th modes are also verified by the experiment. Thus the developed model is to be utilized for the structural design of the real mixer system.

• 한국문헌정보학회지
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• 제40권4호
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• pp.111-139
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• 2006

대학도서관 자료의 전문화, 세분화된 학술정보자료의 공동수집 및 공동이용은 대학 내 연구의 활성화와 대학간 다양화, 특성화, 지역화를 추진하게 할 것이다. 이것은 국가 및 대학 차원에서 대학도서관의 특성화, 차별화 정책을 기반으로 할 때 가능할 것으로 보인다. 이에 본 연구에서는 대학도서관의 주제별 특성화를 기반으로 한 국가적 학술정보공동활용체계를 제안했으며, 구체적으로 두 가지 방안을 제시하였다. 첫째 한국교육학술정보원을 중심으로 형성된 협력망을 이용하는 방법과 둘째. 주제 또는 지역별로 형성된 각종 협의회를 중심으로 주제별 특성화를 유도하고 이를 활용하는 방법이다.

• Reproductive and Developmental Biology
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• 제37권4호
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• pp.185-192
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• 2013

Many countries have implemented genetic evaluation for fertility traits in recent years. In particular, reproductive trait is a complex trait and need to require a system-level approach for identifying candidate genes related to the trait. To find the candidate gene associated with reproductive trait, we applied a weighted gene co-expression network analysis from expression value of bovine genes. We identified three co-expressed modules associated with reproductive trait from bovine microarray data. Hub genes (ZP4, FHL2 and EGR4) were determined in each module; they were topologically centered with statistically significant value in the gene co-expression network. We were able to find the highly co-expressed gene pairs with a correlation coefficient. Finally, the crucial functions of co-expressed modules were reported from functional enrichment analysis. We suggest that the network-based approach in livestock may an important method for analyzing the complex effects of candidate genes associated with economic traits like reproduction.

• 대한기계학회논문집A
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• 제38권2호
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• pp.115-120
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• 2014

본 연구에서는 다물체 동역학 해석 소프트웨어인 RecurDyn 을 이용하여 풍력 발전기를 쉽게 모델링하고 동적 거동 해석을 수행할 수 있는 기법을 개발하였다. 풍력 발전기는 타워, 너셀, 허브, 그리고 블레이드로 구성되어 있다. 타워와 블레이드는 탄성체로 가정하였고 탄성효과를 고려하기 위하여 탄성체 이론을 이용하여 모델링 하였다. 바람의 속도는 일정하다고 가정하였고 날개 요소 운동량 이론을 이용하여 공력하중을 모델링 하였다. 이를 통해 계산된 공력을 풍력 발전기에 적용시키고 동적 거동 해석을 수행하였다. 해석의 타당성을 검증하기 위하여 풍력 발전 시스템 상용 소프트웨어인 GH-Bladed를 이용한 해석결과와 비교하였다.

• 한국콘텐츠학회논문지
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• 제3권2호
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• pp.78-86
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• 2003

이동통신이 대중화되면서 서비스확장을 위해 무분별하게 기지국 건설함으로써 발생하는 기지국간의 중복투자 및 자연훼손을 방지하기 위하여 정통부에서는 기지국 공용화를 요구하였다. 본 연구에서는 수도권 지하철 역사내에 설치된 공용중계기에서 발생되는 전원 불량 등의 장애요인 및 장비, 시설 불량 또는 지하철 터널 구간에서 발생되는 통신 서비스에 대한 문제점을 조사하여 분석하였다. 본 논문의 내용은 공용화 서비스에서 놓은 품질의 서비스를 제공하고 앞으로 추진될 IMT-2000 또는 제4세대 이동통신 공용화에 중요한 기초자료가 될 것이다.

• 한국항만경제학회지
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• 제18권2호
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• pp.109-133
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• 2002

The China entered World Trade Oganization(WTO) last year, thus opening its border to more - and freer - trade. With its foreign trade rapidly expanding and with economic growth continuing at a substantial -rate, China will be the largest container traffic generating country in the world. In the light of this potential trade bonanza, regional ports in North-East Asia strive to gain a competitive-edge. The Port of Busan, the world's third largest container port, wants to capture a significant share of the china's container cargoes. In this circumstance, development strategies of the Port of Busan are suggested as follows. First, to cope with increasing volumes, the New Busan Port on Gaduk island should be constructed without failure. Second, it is necessary to add modernized high-performance gantry cranes and to train crane operators' skill. Third, it needs to apply Dwell Time- Sliding Scale System for transshipment cargoes. Fourth, it needs to develop the EDI network in terminal areas or adjacent hub ports to exchange trustworthy and satisfactory informations Fifth, port authority -needs to enlarge designated Free Trade Zone to facilitate the free flow of cargoes. Sixth, the restoration of rail links between North and South Korea is abundantly clear. Thus it needs to enlarge railroad facilities in advance. Seventh, it needs to establish the Port Authority of Busan immediately. Finally, it needs to strengthen port sales and to open events like 'Marine Week 2001' regularly to attract potential canters or big shippers.

• Wind and Structures
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• 제32권2호
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• pp.81-87
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• 2021

The aim of the current study is to compare the performance of large 2 MW and 3 MW wind turbines operating on existing onshore wind farms using Blade Element Momentum (BEM) theory and Angular Momentum (AM) theory and illustrate the performance characteristic curves of the turbines as a function of wind speed (U∞). To achieve this, the measurement data obtained from two different Wind Energy Power Plants (WEPPs) located in the Hatay region of Turkey was used. Two different horizontal-axis wind turbines with capacities of 2 MW and 3 MW were selected for evaluation and comparison. The hub-height wind speed (UD), turbine power output (P), atmospheric air temperature (Tatm) and turbine rotational speed (Ω) data were used in the evaluation of the turbine performance characteristics. Curves of turbine power output (P), axial flow induction factor (a), turbine rotational speed (Ω), turbine power coefficient (CP), blade tip speed ratio (λ), thrust force coefficient (CT) and thrust force (T) as a function of U∞ were obtained for the 2 MW and 3 MW wind turbines and these characteristic curves were compared. Results revealed that, for the same wind speed conditions, the higher-capacity wind turbine (3 MW) was operating at higher turbine power coefficient rates, while rotating at lower rotational speed ratios than the lower-capacity wind turbine (2 MW).

• Steel and Composite Structures
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• 제47권1호
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• pp.1-17
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• 2023

This paper deals with the free vibration behavior of rotating composite beams reinforced with carbon nanotubes (CNTs) under uniform thermal loads. The temperature-dependent beam material is assumed to be a mixture of single-walled carbon nanotubes (SWCNTs) in an isotropic matrix and five different functionally graded (FG) distributions of CNTs are considered according to the variation along the thickness, namely the UD-uniform, FG-O, FG-V, FG-Λ and FG-X distributions where FG-V and FG-Λ are unsymmetrical patterns. Considering the Timoshenko beam theory (TBT), a new finite element formulation of functionally graded carbon nanotube reinforced composite (FGCNTRC) beam is created for the first time. And the effects of several essential parameters including rotational speed, hub radius, effective material properties, slenderness ratio, boundary conditions, thermal force and moments due to temperature variation are considered in the formulation. By implementing different boundary conditions, some new results of both symmetric and non-symmetrical distribution patterns are presented in tables and figures to be used as benchmark for further validation. In addition, as an alternative advanced composite application for rotating systems exposed to thermal load, the positive effects of CNT addition in improving the dynamic performance of the system have been observed and the results are presented in several tables and figures.

• 산경연구논집
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• 제9권12호
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• pp.55-61
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• 2018

Purpose - It suggests that making a policy and strategies for a way of Dubai has a strong priority strategy on science and technology by using much oil dollars to prepare risk when oil dollar's decrease. This has been now investigated how the leading innovator has changed the periphery countries. Research design, data, and methodology - Analyze policy, status, what other neighbouring Middle East countries also want to benchmark a successful case of a leading Dubai strategy. Higher manpower is needed absolutely to develop S&T. and etc. Dubai and Arab countries establish university to nurture as well as invite the talented manpower from overseas to recover deficient manpower. Dubai built totally academy city and invited branch of the overseas famous university, and Saudi Arabia built university(KAUST) and invite faculty and support good scholarship for students. Abrab countries especially, This is studied the process of differentiating and integrating the migrant workers of these cities into the globalized cities. This has resulted in large-scale employment for foreign and local companies in these cities and the spread of science and innovation. Results - Dubai supports venture or SMEs by using a strong priority strategy and attracts foreigner's investor, with which the neighbouring countries have been preparing together for 4th wave. It demonstrates that the gravitational model has been activated from neighboring countries of innovation science to create Dubai's hub. The maturity of long-term urban innovation is related to innovation capability through the national response and review. As a result, the flow of skilled international migration has been localized because of the mutual intersection with the local employment structure, and the development has spread as it spreads to neighboring countries. Conclusion - For the exploiting of new Distribution market in the neighbouring countries, Middle East countries' a strong priority strategy on S&T and education system give an influence on economic situation of the 4th wave in the world and world order of leading by USA, Japan, or EU, and etc. This is due to the creation of clusters in the form of SEZs, friendly industrial policies and world-class infrastructure and innovation development. Its neighbours benchmark the cases of distribution of science innovation and centralizes the surrounding people.

• 한국항만경제학회지
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• 제36권3호
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• pp.75-98
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• 2020

세계 주요 허브항만이 되기 위한 각국의 치열한 항만 물동량 싸움에서 한국이 동북아시아 및 글로벌 물류 중심기지로 발돋움하기 위해 현실적이며 효율적인 정책 필요성이 강력히 요구된다. 본 연구의 목적은 동북아시아 물류 중심기지화를 위한 우리나라 항만들의 경쟁력 확보정책의 일환인 항만 인센티브 제도를 비교·분석하고 이를 이용자가 느끼는 서비스품질의 중요도와 성취도를 비교 분석함으로써 항만의 경쟁력제고를 위한 항만지원방안을 모색하고자 하는데 있다. 따라서 본 연구에서는 우리나라 항만의 인센티브제도 개선방향에 대해 연구 및 이용자 및 전문가를 대상으로 한 설문을 바탕으로 IPA분석을 실시해 보았다. 결과적으로 신규 기항선사 및 수출화주, 수입화주에 대한 인센티브 지급과 합리적인 인센티브 부여 기준마련에 대한 요인은 유지 관리해야 한다고 나타났다. 인센티브 청구절차의 간소화, 전산화, 터미널 운영사 인센티브 및 기존 인센티브외 부가적 인센티브 부여는 개선대상영역으로 나타났으며, 이는 정책을 결정하는 기관에서 제도개선을 위한 의견수렴과 이용자들의 관심을 높이도록 고려해야 할 것이다. 중점개선 영역 요인은 기존기항 선사에 대한 인센티브 제공이며, 이는 기존기항 선사들에 대한 인센티브 제공기준을 재검토하여 좀 더 체계적이며 효율적인 정책으로 적극적인 관리가 필요하다고 볼 수 있다.