• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.38-46
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• 2001

To assess the oil-containment effectiveness of tandem oil fences placed in currents, the movement of oil droplets in the fore and aft region of the fences is investigated by experimental and numerical methods. The effect of the flexibility of the fence skirt of single fence on the fence effectiveness is also investigated. Laboratory experiment is conducted to trace the path of a spherical solid particle of equivalent density to an oil droplet which was released in a uniform stream ahead of a model oil fence. Depending upon the releasing position and the flow condition there, it was observed that the particle floated up to the free surface, collided with the fence, or escaped below the fence. By analyzing the droplet trajectories, a numerical method is developed to predict the region ahead of the fore fence where an oil droplet initiating its motion eventually escapes beneath the fence. The effect of the relative sizes of the drafts of the fore and aft fences, the fence separation, and the bottom depth of the sea bed on the effectiveness of tandem fences is investigated using the numerically obtained trajectories of oil droplets.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.37-49
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• 2008

Services are reusable units in business level. Ubiquitous computing provides computing services anytime and anywhere. The combination of both is becoming an important paradigm of computing environment. Fundamentals of services require flexibility and interoperability, and key elements of ubiquitous modeling require interoperability and context-awareness. There are two kinds of methods to identify services. The top-down approach is based on business process, and the bottom-up approach is based on components. The first approach depends on experts' intuitions, while the second approach suffers the incapability of expressing non-functional expression through components. Although a feature-based approach is capable of expressing non-functional expression and identifying services in ubiquitous environment, the research on this issue is not adequately addressed by far. To promote this research, this paper proposes a feature-based method to identify services in ubiquitous computing. The method extracts initial-candidate-services from a feature model. Then, the ultimate services are identified through optimizing and analyzing the candidate-services. The proposed method is expected to enhance the service reusability by effectively analyzing ubiquitous domain based on feature, and varying reusable service units.

• Journal of the Ergonomics Society of Korea
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• v.34 no.1
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• pp.19-27
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• 2015

Objective: The aim of this study is to investigate how well eye movement times in visual target selection tasks by an eye input device follows the typical Fitts' Law and to compare vertical and horizontal eye movement times. Background: Typically manual pointing provides excellent fit to the Fitts' Law model. However, when an eye input device is used for the visual target selection tasks, there were some debates on whether the eye movement times in can be described by the Fitts' Law. More empirical studies should be added to resolve these debates. This study is an empirical study for resolving this debate. On the other hand, many researchers reported the direction of movement in typical manual pointing has some effects on the movement times. The other question in this study is whether the direction of eye movement also affects the eye movement times. Method: A cursor movement times in visual target selection tasks by both input devices were collected. The layout of visual targets was set up by two types. Cursor starting position for vertical movement times were in the top of the monitor and visual targets were located in the bottom, while cursor starting positions for horizontal movement times were in the right of the monitor and visual targets were located in the left. Results: Although eye movement time was described by the Fitts' Law, the error rate was high and correlation was relatively low ($R^2=0.80$ for horizontal movements and $R^2=0.66$ for vertical movements), compared to those of manual movement. According to the movement direction, manual movement times were not significantly different, but eye movement times were significantly different. Conclusion: Eye movement times in the selection of visual targets by an eye-gaze input device could be described and predicted by the Fitts' Law. Eye movement times were significantly different according to the direction of eye movement. Application: The results of this study might help to understand eye movement times in visual target selection tasks by the eye input devices.

• STI Policy Review
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• v.3 no.2
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• pp.92-110
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• 2012

An active policy role is suggested for collaboration that will enhance national level Science and Technology (S&T) capabilities. In contrast, some studies see a limited role of policy support for collaborative S&T research at the individual level (including research groups or institutional levels) due to their self-organizing nature. Two views on S&T collaboration look at different levels but existing research largely ignores the context of developing countries. This paper shows how S&T collaborations between Brazil and Korea have developed over the past two decades. The paper indicates the gaps between initiation and the actual establishment of collaborative research at national and individual levels, differences in the focus areas of research, differences in resources and project planning, and the nature of collaborations. Collaborative research activities at the national level were initiated before the individual level but activated later than the individual level; in addition, the focus areas of research were laid down earlier at the national level with individual collaborations focused on different areas. Project types remained different at each level (i.e. top-down and bottom-up) or with a slightly changing mix. This study suggests appropriate policy measures (such as the timely and effective information collection of activities at different levels and proactive coordination) that could reduce the gaps in the timing and alignment of research areas. This paper also alludes to an evolutionary model to develop S&T collaboration among developing countries.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.137-144
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• 2010

Up to now, common studies of top base have concentrated upon bearing capacity and settlement by in-situ loading test in Japan and Korea. But most of all preceding study for top base must analyze how to deliver overburden loading on bottom of foundation. Therefore, in this study, the stress delivery mechanism of Top-Base Foundation developed in Japan and Floating Top Base developed in Korea is investigated through numerical analysis and laboratory model test. Analyzing the load delivery mechanism of top base, it was found that the division rate of load reduction of top base for overburden load was largest in peripheral skin friction between the top base and the crushed stone. Further, total stress dispersion angle of Top-Base Foundation including internal stress dispersion effect of top base was $41.8^{\circ}$ and total stress dispersion angle of Floating Top Base was $44.5^{\circ}$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.117-118
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• 2012

As the technical standard of hydrographic data was transferred from S-57 to S-101, a standard system was set up for producing the next generation ENCs but also various maritime safety information. ECDIS that display a S-57 ENC and include a navigation support function, should be developed considering new standard. S-10X data and e-Nav information can be used in this system. In this study, an implementation mechanism of S-100 standard was analyzed for design of navigation support system based on S-100. From the results, it was designed as loading module of S-10X data, display module of SENC, navigation supporting module. Also, this study considered a next generation ENC, a bathymetric grid data, an electronic nautical publication as an input information.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.9-9
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• 2019

기후변화로 인한 다년 가뭄은 매년 증가하여, 충청남도에 위치한 보령댐과 보령댐으로부터 용수를 공급받는 지자체의 시민들 또한 2015년부터 2017년까지 지속된 가뭄으로 인해 총 127일 동안의 생 공용수 급수조정으로 인한 불편함을 경험하였다. 지금까지 시행된 국내의 다양한 가뭄 피해 저감 정책 설립 과정은 대부분 일방적인 하향식(top-down) 의사결정 과정을 바탕으로 진행되었고, 이는 이해당사자와 정책결정자간의 갈등을 유발했다. 이로 인한 피해를 방지하기 위해 본 연구에서는 참여형(bottom-up) 의사결정 과정 중 하나인 비전공유계획을 충청남도 기후변화 적응 물관리정책 협의회를 통해 적용하였다. 또한, 비전공유계획의 핵심 요소인 비전공유모형을 시스템 다이내믹스 모형의 특성을 포함하여 개발하고자 STELLA Architect 소프트웨어로 보령댐 및 8개 지자체를 포함한 저수지 운영모형을 구축하였고, 총 3차례의 소위원회를 거쳐 수렴한 이해당사자의 요구사항에 따라 개발한 모형을 보완하였다. 구축한 모형으로는 미래에 발생 가능한 가뭄의 위험을 포함하고 있는 기후변화 시나리오에 대한 모의를 진행하였고, 보령댐과 보령댐으로부터 용수를 공급받는 충청남도 서해수역 지자체의 가뭄으로 인한 취약성을 평균부족횟수, 평균부족기간, 평균부족량으로 표현하였다. 모의 결과, 보령댐은 8개 지자체보다 가뭄에 상대적으로 더 취약하며, 8개 지자체에서는 가뭄 대응 대책이 주로 계획되어 있는 지역과 모의에서 가뭄이 발생하는 지역의 불일치로 인한 피해가 발생할 수 있음을 확인하였다. 또한, 다른 평가지표에 비해 예측하기 어려운 평균회복기간에 대해서는 댐과 지자체에서 이를 고려하는 것이 필요하다. 비전공유모형을 통한 가뭄 취약성 분석 결과를 미래 회의에서 이해당사자와 공유하고, 용수 공급처과 수요처의 입장에서 용수 부족을 해소할 방안을 모형에 적용함으로써 미래 가뭄 대응 정책 수립 과정에는 참여형으로 의사결정을 할 수 있음을 제안하였다.

• Journal of the Korean Geotechnical Society
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• v.35 no.7
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• pp.5-14
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• 2019

In this study, a prototype abutment was constructed to establish a safety assessment technique of pier and a series of non-destructive tests using impact load. The surcharge load was loaded from 0 tonf to 2.5 tonf on the prototype abutment, and maximum surcharge load was up to 25 tonf. To analyze the behavior of the piers according to the direction of impact, a total of three types of analysis were performed: the direction of the pier, the direction perpendicular to the pier, and the outer direction of the pier. The height of the impact was also tested at each top and bottom. The measuring instrument used an accelerometer to measure the acceleration response when impacted. Based on the series of experimental results, specific values were calculated according to the direction of an impact and the surcharge load using the Fast Fourier Transform (FFT). In addition, the phase difference was used to analyze the pier from the primary 1st mode to the 4th mode.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.28-34
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• 2019

In this study, pin-fin arrays, which are widely used for cooling turbine blades, were studied. The vortex generator in pin-fin arrays is located in front of the circular tube. The cross-section of the vortex generator is NACA-9410. The purpose of this study is to analyze heat transfer performance and flow characteristics of pin-fin arrays. The position of vortex generator is changed with the vertical flow direction on the bottom wall. Pin-fin arrays were calculated with 6000, 10000 and 15000 Reynolds number. The commercial program ANSYS v18.0 CFX and the turbulence model $k-{\omega}$ SST were used. As a result, the heat transfer performance increased up to 5.8% and pressure loss increased less than 1%.

• Korean Journal of Organic Agriculture
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• v.30 no.2
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• pp.241-253
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• 2022

The negative impact of climate change on the agricultural sector is rapidly increasing, and it is urgent to prepare policies at the government level to mitigate it. In the case of Rwanda's agricultural sector, which lacks the government's budget and farmers' capital, efficient and effective policy implementation is of paramount importance. To this end, rather than establishing related policies in the public sector from the top down, it is necessary to establish a bottom-up customized policy that is reflected in policy establishment by identifying the characteristics and behaviors of farmers who actually participate in adaptation activities. In this study, the effects of farmers' characteristics and farmers' perception status/adaptation status to climate change on the selection of adaptation methods for climate change were analyzed. 357 rice farmers randomly selected from Eastern Rwanda were surveyed to explore the information related to farmers' perception to climate change and adaptation methods as well as basic information of the farm. Research shows that the probability of selecting a variety of adaptation methods rather than not responding to climate change increases the younger the age, the higher the education level, and the easier access to climate information and credit. As a policy proposals, it is judged that public support such as strengthening agricultural technology support services, including more detailed guidance for elderly and low-educated farmers, and improving access to farm loan services by agricultural financial institutions is needed. In addition, it is necessary to adjust the planting time and cultivation method, provide timely information related to climate change, and provide crop variety improvement services to farmers.