• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1353-1362
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• 2014

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.53-60
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• 2013

The compaction control method of national road substructure is using field density test to determine the relative compaction and plate bearing test to check the load bearing capacity. However, these two tests digitize a construction site manager's judgment based on his experience, so mechanical basis is weak. Resilient modulus method, which is recently being used to resolve such problem, is evaluated as a rational design method of pavement structure that can rationally reflect the stress-strain state of pavement materials that is caused by the condition of load repetition of vehicle load. However, the method of measuring the resilient modulus is difficult and lengthy, and it has many problems. To replace it, light falling weight test is recently being proposed as a simple test method. Therefore, this research uses dynamic plate loading test, which quickly and simply measures the elastic modulus of the subgrade and sub-base construction and site of maintenance, to judge the possibility of compaction control of the stratum under the road, and it proposes relation formula by analyzing the result of static load test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1166-1176
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• 2011

The prospect in opening the arctic trade transportation route on a year-round basis offers vast opportunity of exploring untapped resources and shortened navigational routes. In addition, the environment's remoteness and lack of technical experiences remains a big challenge for the maritime industry. With this, engine designers and makers are continually investigating, specifically optimizing propulsion shafting system design, to meet the environmental and technical challenges of the region. The International Association of Classification Society, specifically machinery requirements for polar class ships(IACS UR13), embodies the propulsion shafting design requirements for ice class vessels. However, the necessity to upgrade the various features of the unified rules in meeting current polar requirements is acknowledged by IACS and other classification societies. For the polar class propulsion shafting system, it is perceived that the main source of excitation will be the propeller - ice load interaction. The milling - and the impact load, in addition to the load cases interpreted by IACS, contribute greatly to the overall characteristic of the system and due considerations are given during the propulsion design stage. This paper will expound on the excitation load estimation factors affecting the dynamic response of the different propulsion shafting system design. It is anticipated that detailed understanding of these factors will have a significant role during propulsion shafting design in the future.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.86-91
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• 2008

Ships operating in littoral sea are likely to be subjected to accidental load such as stranding. Once she has damage on the hull structure, her ultimate strength will be reduced. This paper is to investigate the effect of the stranding damage on ultimate strength of ship structure by using a series of collapse tests. For the experiment, 720 mm $\times$720 mm in section and 900mm in length of five box-girder models with stiffeners were pre- pared. Of the five, one has no damage and faur have an diamond shaped damage which represents the shape of rock section in seabed. The damage size is different between models. Among the damaged models, the damages of 3 of them were made by cutting the plate and one by pressing to represent stranding damage. Experiments were carried out under pure bending load and the applied load and displacements were recorded. The ultimate strength is reduced as the damage size increases, as expected. The largest damaged model has the damage size of 30% of breadth and its ultimate strength is reduced by 21% than that of no damaged one. The pressed one has lower ultimate strength than cut one. This might be due to the fact that the plate around the pressed damage area effect negatively on the ultimate strength.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.623-630
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• 2007

Grouting materials are used for the unification of superstructural and substructural body like bridge seat (shoe) or machinery pedestal and e.t.c by filling their intercalary voids. Accordingly, grouting materials have been developed and used mainly with products of high strength because those materials are constructed specially in a part receiving large or impact load. In this situation, the structural body constructed by grouting materials with high stiffness-centered (caused by high strength) products is apt to cause brittle failure when receiving over a limit stress and to cause cracks according to cumulative fatigue by continuous and cyclic load. In addition, grouting materials are apt to cause cracks by using too much rapid hardening agents that give rise to high heat of hydration to maintain high strength at early age. In this study, to overcome these problems, cement type grouting materials including powder of waste tire and resin as elastic materials which aim to be more stable construction and to be improvement of mother-body's unification are developed and endowed with properties of high toughness and high durability add to existing properties of high flowability, non-shrinkage and high strength. Besides, this study contribute to of for green construction materials for being possible recycling industrial waste like waste tire and flyash. On the whole, seven type mixing conditions are tested and investigated to choose the best mixing condition.

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.50-57
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• 2011

This study investigates the structural safety of typical greenhouse to be utilized for developing plant factory. New long-span greenhouse systems were presented according to the results of structural analyses performed by finite-element program, ABAQUS. Reasonable values of design loads such as wind and snow loads in the Greenhouse Design Specifications (1995) were applied to check the new greenhouse systems. It was concluded that the new greenhouse systems were consistently safe enough to resist to both wind load and snow load. The new greenhouse system can be used to make simple and economic plant factory.

• Journal of Bio-Environment Control
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• v.19 no.2
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• pp.63-69
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• 2010

This study was implemented to clarify the effect of a supplementary pole on the increment of safety snow-depth for the single-span plastic greenhouses which had been run as standardized facilities for 10 to 15 years till April, 2007. In the previous work, some of the basic ideas of the use of a temporary pole were discussed, but application was restricted to both 2-D and the cases which took rafter's specifications into no consideration, and there was also much less experimental information available. So, by modeling the house as the 3-D frame structure, the present study attempted to provide a comprehensive review of the pole's effect through structural analyses as well as measurements. Structural analyses abnormally revealed that the pole regardless of its interval had a negative effect on the structural stability. The results was certainly inconsistent with practical experience and hence implied a necessity of reinforcing the roof purlin. Accordingly, with the purlin being sufficiently reinforced, the plastic greenhouse with the pole's interval of 3~4 m had two times safety snow-depth more than that of the plastic greenhouse without the pole. And the safety snow-depth of five types of the single-span plastic greenhouses according to the pole's intervals was presented.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.73-77
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• 1996

정보는 의사결정자들의 수주에 있을 때 기업에 있어 강력한 경쟁무기가 된다. 의사결정자들의 정보에 대한 이러한 필요성을 충족시키기 위해서 데이타는 운영시스템(Operational System)에서 추출되어 데이타웨어하우스에 저장된다. 데이타웨어하우스는 핵심 비지니스영역(key business dimension)에 의해 정리된 historical data를 저장한다. 이러한 의사결정자들을 위한 데이타웨어하우스 정보의 전달은 기존의 클라이언트/서버 시스템 하에서는 많은 지원을 요구한다. 즉 기존 클라이언트/서버 시스템 하에서는 사용자들의 접근을 위해 데이타가 추출되고 조직화되어지고 나면, 반드시 분석 소프트웨어가 각 사용자의 컴퓨터에 설치되어야 하고 외부의 사용자를 위한 새로운 운영자가 고용되어야 한다. 사용자의 다양한 요구 그리고 계속적 사용자의 교체는 사용자 지원에 있어 심각한 기업부담으로 작용한다. 또한 클라이언트/서버 시스템에서는 기업외부의 정보 이용자들에게 정보를 제공하는데 있어 장소적 한계점을 가지고 잇다. 인트라넷과 인터넷은 이러한 클라이언트/서버 시스템 환경의 문제에 대해 해답을 제시한다. 인트라넷은 데이타웨어하우스로의 접근을 간단히 할뿐만 아니라 의사결정자들의 정보의 공유와 상호분석의 새로운 단계를 제공한다. 그리고 인터넷은 기업 외부 어디에서나 기업이 제공하는 정보를 이용하고자 하는 사람들에게 접근의 편의성을 제공한다. 즉 데이타웨어하우스의 목표와 인트라넷, 인터넷의 목표는 데이타로의 손쉬운 접근이라는 점에서 동일하다. 이러한 점에 착안하여 인트라넷과 인터넷하에서 운용되는 데이타웨어하우스 시스템 구축을 위한 방안을 제시하고자 한다.다(학생군:8.16kg 작업자군:12.9kg). 심박수를 이용한 생리학적 연구에서는 평균 심박수가 거의 100 이하를 유지하므로써 피실험자들이 8시간 작업기준으로 보아 무리가 없는 최대허용 하중을 결정하였음을 보였다. 또한 각 운반작업에 대한 최대허용 하중을 예측하는 회귀모형을 제시하였다.아직 정립되어 있지 않은 분산 환경하에서의 관계형 데이타베이스의 데이타관리의 분류체계를 나름대로 정립하였다는데 그 의의가 있다. 또한 이것의 응용은 현재 분산데이타베이스 구축에 있어 나타나는 기술적인 문제점들을 어느정도 보완할 수 있다는 점에서 그 중요성이 있다.ence of a small(IxEpc),hot(Tex> SOK) core which contains two tempegatlue peaks at -15" east and north of MDS. The column density of HCaN is (1-3):n1014cm-2. Column density at distant position from MD5 is larger than that in the (:entral region. We have deduced that this hot-core has a mass of 10sR1 which i:s about an order of magnitude larger those obtained by previous studies.previous studies.업순서들의 상관관계를 고려하여 보다 개선된 해를 구하기 위한 연구가 요구된다. 또한, 준비작업비용을 발생시키는 작업장의 작업순서결정에 대해서도 연구를 행하여, 보완작업비용과 준비비용을 고려한 GMMAL 작업순서문제를 해

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.35-39
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• 2004

Ship structures are basically an assembly of plate elements and the load-carrying capacity or the ultimate strength is one of the most important criteria for safety assessment and economic design. Also, Structural elements making up ship plated structures do not work separately, resulting in high degree of redundancy and complexity, in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed simplifications or idealizations must essentially be made considering the accuracy needed and the degree of complexity of the analysis to be used On this study, to investigate effect of modeling range, the finite element method are used and their results are compared varying the analysis ranges. The model has been selected from bottom panels of merchant ship structures. For FHA, three types of structural modeling are adopted in terms of the extent of the analysis. The purpose of the present study is to numerically calculate the characteristics of ultimate strength behavior according to the analysis ranges of stiffened panels subject to uniaxial compressive loads.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.252-257
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• 2015

Fruit cracking and vine leaf spot of grapes tend to occur when the plants were directly exposed to rain under outdoor culture. Rain shelter facility can be an alternative method to prevent the cracking and disease of grape, but it also has some limitations in practical usages. We designed rain shelter facility which can completely shut out the rain and ventilate naturally, and it was upgraded to meet the standards of disaster prevention against snow and wind load. The newly developed rain shelter has two-story roof structure, and the $2^{nd}$ floor roof was equipped over $1^{st}$ floor roof at a distance of 40cm. For natural ventilation and water proof, the upper roof protruded about 50cm from the ridge of a $1^{st}$ floor roof. The various tests were carried to examine such as grape quality, brown spot and fruit cracking of Campbell Early under the conventional and the newly developed rain shelter facility which was built about $100{\ss}{\check{S}}$. In comparison of temperature between the conventional and the newly developed rain shelter facility when outside temperature was more than $34^{\circ}C$, the inside temperature was recorded as $40.7^{\circ}C$ and $37.4^{\circ}C$, respectively. There was no significant difference between the two facilities when outside was below $32^{\circ}C$ The quality such as soluble solids and marketable fruit was increased, and fruit cracking of grapes and vine leaf spot also drastically diminished in the newly developed rain shelter.