• 한국항만경제학회:학술대회논문집
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• 한국항만경제학회 2007년도 정책세미나 및 국제학술대회
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• pp.255-270
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• 2007

In North-East Asia, Port traffic in Asia-North America sea route has been rapidly increasing due to economic growth in China and ASEAN. Furthermore, the major shipping companies directly call at northern chinese ports like Qingdao, Dalian and Tianjin without passing through Korean ports on Asia-North America sea route. To acquire a port traffic and develop a hub port, governments in North-East Asia have intensively invested in the development of port. Therefore, Busan new port and Gwangyang port have been developed in Korea. According to the medium-long term development planning, the port should give a enormous budget investment for the port facilities construction. So the inaccurate estimation may lead to the unreasonable port development policy. Firstly, based on the estimation of Chiang Bong-Gyu & Yang Hang Jin(2005), this study gave a comparison with the estimation of Ministry of Maritime Affairs and Fisheries(2001) and OSC/Glori(2005). Secondly, taking into account the influence factors for port traffic, this study made an estimation of port traffic for Busan new port. On the basis of this estimation, this study is compared with the estimation of Ministry of Maritime Affairs and Fisheries(2001) and OSC/Glori(2005). In conclusion, in case of the development of Busan new port, based on the estimation of Ministry of Maritime Affairs and Fisheries(2001), this study should the high possibility that the Busan new port will be serious lack of the port facilities in the year of 2011. And according to the OSC/Glori(2005)'s estimation result, there is a lack of the port facilities, though we have modified the port investment plan.

• 한국정보통신학회논문지
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• 제21권8호
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• pp.1498-1507
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• 2017

최근 발표에 따르면, 2020년까지 모바일 데이터 트래픽이 현재의 11배까지 증가 될 것으로 예상된다. 그 중 비디오 트래픽이 70%를 차지할 것으로 예상되는 만큼 방대해지는 모바일 비디오 트래픽의 문제를 해결하기 위해서는 비디오 트래픽의 특성을 이해할 필요가 있다. 최근, 인기 있는 유튜브 비디오와 같은 일부 인기 있는 콘텐츠의 반복적인 요청으로 인해 네트워크 트래픽 오버헤드가 많이 발생한다. 만약 콘텐츠 인기도를 알고 인기 있는 콘텐츠를 미리 캐싱 할 수 있는 네트워크 노드를 구성한다면 이용자의 요청에 대해 캐싱 된 콘텐츠를 이용함으로써 네트워크 오버헤드를 줄일 수 있다. 장치 대 장치 통신, 멀티캐스트, 헬퍼를 통해 비디오 처리량이 기존의 방법보다 약 1.5배에서 2배의 이득이 향상되었다. 또한, 프리픽스 캐싱을 통해 기존의 방법보다 약 0.2배에서 0.5배의 재생 지연이 감소되었다. 본 논문에서는 무선 네트워크 환경에서 콘텐츠 인기도를 기반한 캐싱 기술에 대한 최신 연구를 소개 한다.

• 한국지리정보학회지
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• 제25권2호
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• pp.100-109
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• 2022

한국의 경제성장과 함께 인구와 차량의 대규모 도시 집중에 따라 심각한 도시교통 문제가 초래되고 있다. 혼잡통행료의 징수는 교통수요를 관리하기 위한 가장 효과적인 정책으로 평가받고 있지만 대부분 혼잡이 발생하는 지점이나 교통축을 중심으로 적용되어 그 효과가 제한적이다. 본 연구는 동적 혼잡통행료 징수 체계를 제안하기 위해 부산광역시 206개 교통 분석 존의 평균 통행속도를 이용하여 시공간 큐브 분석(Space-Time Cube Analysis)과 시공간 패턴 마이닝(Emerging Hot Spot Analysis) 기법으로 면적인 개념의 동적 혼잡구역을 도출하였다. 분석 결과, 비 첨두시간인 0시~7시에는 핫스팟이 형성되지 않고, 7시~24시에는 동적 핫스팟이 형성되는 것으로 나타났다. 특히, 특정 시간대(18시~20시)와 특정 지역(서면, 광복동)에 교통 혼잡이 집중하는 것을 확인할 수 있었다. 따라서, 동적 혼잡통행료의 징수를 위한 시공간의 분석을 통해 도심에서의 교통수요 관리의 효과가 극대화될 것으로 기대한다.

• 정보와 통신
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• 제19권6호
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• pp.89-97
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• 2002

Voice revenues are critical to service providers today as they still make up 60% of revenues. Voice is certainly dominant, but the growth is flat. Wireless & data traffic are increasing, resulting in the need for integrating different networks into a unified platform for network efficiency, cost savings and additional revenue opportunities.

• 아시안잔디학회지
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• 제17권2_3호
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• pp.87-97
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• 2003

The growth characteristics of creeping bentgrass seeded in the seaside landfill golf course are as follows. 1. As a result of analysis on the chemical characteristics of soil mixture used for turfgrass ground in this experiment, soil pH was 7.9, which is somewhat higher than the creeping bentgrass reference value of pH 5.5∼6.5; T-N(%) was 0.02, which is proper for the reference value, and trace element too lacked. 2. The cultivar with the fastest water infiltration was Seaside II recorded as 226.2cm/sec, while that with the slowest water infiltration was Pennlinks recorded as 141.1 cm/hr which was too faster than the USGA water infiltration reference value of 15∼30cm/hr. For the surface hardness of turfgrass ground with different cultivars, no statistically significant variation was found between the Penncross grass and the Pennlinks recorded as 18.6mm and 19.1 mm, respectively. The soil penetration was the highest in Pennlinks recorded as 7.6kg/$\textrm{cm}^2$ and lowest in Penn A-1 as 6.1kg/$\textrm{cm}^2$. 3. As a result of evaluation on visual quality at the early stage of growth, Penncross showed the most excellent visual quality compared to the others. However, Penn A-1 showed the most excellent visual quality at a late stage of growth around Sep. 17, 2003, and it was also excellent in the evaluation of visual color. Seaside II showed higher density around the root and the longest root length and was highly resistant to salt compared to others, but the initial sprouting rate was not satisfied, and the visual quality in the summer season was inferior to others. 4. As a result of measurement of the traffic injury, Penncross showed the most tolerant to the traffic stress and Pennlinks showed the most susceptible.

• Wind and Structures
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• 제36권3호
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• pp.175-200
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• 2023

The large eddy simulation (LES) of the flow around a circular cylinder is not only affected by the sub-grid scale (SGS) model but also by the grid resolution of the computational domain. To study the influence of different grids on the LES results, the LES simulations of the flow around a circular cylinder with different grids at Reynolds number (Re) = 3900 was performed. A circular computational domain with different radial growth rates and circumferential and spanwise grid numbers was adopted for the simulations. Meanwhile, the aerodynamic forces, wind pressure coefficients, mean and instantaneous flow fields, and the effect of grid resolution on them were comprehensively analyzed. The results indicate that the lift coefficient, wind pressure coefficient, and recirculation length are significantly affected by the radial growth rate of the grid and the circumferential grid number. The spanwise grid number has a significant influence on the three-dimensionality of the flow and plays an important role in velocity fluctuations in the wake region. Nevertheless, the aerodynamic coefficients and recirculation length are not sufficiently sensitive to the grid number in the spanwise direction. By comparing the results, it can be concluded that suitable and reliable LES results can be obtained when the radial growth rate is 1.03 or 1.05, the circumferential grid number is 160, 200, or 240, and the spanwise grid number is 64. A radial growth rate 1.05, circumferential grid number 160, and spanwise grid number 64 are recommended to reduce the grid amount and further improve the efficiency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.432-436
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• 2010

This paper investigates the productivity growth in Korean railway lines. The productivity growth is calculated by a process of measuring of pure efficiency change index(PECI), scale efficiency change index(SECI), and technical change index(TCI), using Data envelopment analysis (DEA) method. The data cover the period 1990~2007; 1990~2003 are the pre-structural reform years and the post-structural reform years are 2005~2007. The framework for the analysis is Malmquist Productivity Index (MPI) of the to investigate the impacts of structural reform on productivity growth, respectively. The inputs considered are the length of operating line, the number of staff, the number of coach and wagon, and the outputs are the trains movement of passenger and freight, and the traffic of passenger and freight.

• 한국광학회지
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• 제24권6호
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• pp.297-310
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• 2013

스마트 기기, 클라우드 서비스, 광가입자망 등의 보급에 따른 멀티미디어 기반의 대용량 인터넷 트래픽의 급속한 증가로 통신 수요는 연 40%이상씩 증가하고 있다. 이러한 대역폭 증가를 수용하기 위해서 광통신용 광부품의 진화도 각 계층별로 빠르게 진행되고 있다. 가입자망에서는 변조속도 증가와 더불어 파장다중방식의 도입이 시작되고 있고, 매트로망에서는 보다 효율적인 망 운용을 위해 차세대 ROADM에 대한 개발이 진행중이며, 장거리 통신에서는 코히어런트 통신 기반의 새로운 변조방식이 도입되어 스팩트럼 효율을 향상시키고 있다. 본 논문에서는 이러한 폭발적인 통신 대역폭 증가 요구에 따른 광통신망의 진화와 이를 수용하기 위한 고속화, 효율화, 저전력화로 발전하고 있는 핵심 광부품에 대해 살펴본다.

• 한국항만경제학회:학술대회논문집
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• 한국항만경제학회 2006년도 국제학술대회
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• pp.211-233
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• 2006

The purpose of this study is to analyze traffic volume between the Korean container ports located at the west coast and northern Chinese ports and then the distribution trend of container between Korea and China. The findings of the study are as follows. First, Container traffic between western Korean ports and northern Chinese ports has been increasing due to an increasing trade volume between both countries and geographical accessibility. Second, Seoul and neighboring area tend to use the trade route between the western ports and northern Chinese because of lower logistics costs and time-saved advantage compared to another ports. Third, the growth of the western ports did depend mainly on the northern China oriented growth. Such a fact could leads to the overlapping investment in port development in Korea and another intense competition among national ports to attract cargoes and liners. Therefore, port development policy considering the characteristics and function of national ports have to be established. and also alternatives and strategies for improving the competitive edge of small and medium sized shipping lines against the opening of shipping market have to be worked out.

• Journal of Biosystems Engineering
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• 제34권6호
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• pp.397-403
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• 2009

This study was carried out to investigate the present status of subsoil compaction, and subsoil compaction management in orchard as a basic study for developing a self-propelled explosive subsoiler. Subsoil compaction was evaluated using the soil penetration resistance. Soil cone index was measured using the DIK 5520 type cone penetrometer in several fruit farms such as apple, pear, peach and grapes during growing seasons of these fruit in Jecheon, Gamgok, Choongju, Cheonan and Hwasung areas. Most of the subsoil managing machinery were either explosive type or digging type attached to the tractor or power tiller and turning radius of this machine was more than 3-5 m. Many of the farmers wanted to use the subsoiler which can put lime into soil and rupture soil at the same time. For most of the orchard fields, soil penetration resistance in vehicle traffic area was increased quickly and reached about 1.0 MPa in 5 cm soil depth. As the soil depth increased to 15-20 cm, cone penetration resistance reached about 2.0-2.5 MPa which restricted root growth seriously. Thus it was concluded that one of the main reason for increasing the soil compaction in orchard fields is agricultural vehicle traffic. In the vicinity of fruit trees, compaction is not so serious compared to that of the vehicle traffic area, but as the soil depth increased to 20-25 cm, in most of the orchard fields soil penetration resistance reached about 2.0-2.5 MPa which is the root growth-limiting value. Considering the rooting depth of fruit trees which ranged 30-60 cm for apple, pear and peach, and 20-30 cm for grape, it is necessary to loosen the subosoil and improve the subsoil conditions using subsoiler.