• Membrane Journal
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• v.22 no.5
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• pp.352-358
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• 2012

In this study, we found structure-property relationship for pressure retarded osmosis (PRO) membrane, between BPS-XX and BisA-XX having similar structure but different free volume. And this comparison was subdivided by controlling its sulfonation degree. BPS-XX and BisA-XX were prepared via a polycondensation reaction. The degree of sulfonation were 20 to 60 mol.%. And they were fabricated to membrane. Characteristics were analyzed to verify of free volume. And the results showed that increase of free volume normally lead to increase permeability and decrease selectivity in equivalent molecule structure. Finally, in the permeability-selectivity results, we conclude high permeability and selectivity membrane can be prepared by controlling molecular structure and free volume.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.11-15
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• 2008

By considering manufacture and economic factor, the steel pipes have been employed for water supply pipeline with large diameter. The standard to decide a thickness of pipe was provided by the waterworks standard (Ministry of Construction & Transportation, 1992) in South Korea. However, there was no the systematic standard to confirm a thickness of pipe in it. Thus, it should be able to apply to unsuitable the Stewart formula for the buried pipe to design for an optimum thickness of pipe. In order to meet revised the waterworks standard (The Ministry of Environment, 1997), it has been considered both the ground condition and all of the stresses to compute a thickness of pipe. As a results, a method is suggested to determine thickness of pipe after comparing and validating the obtained results with the established results from the Stewart formula.

• Journal of Ship and Ocean Technology
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• v.6 no.2
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• pp.12-22
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• 2002

Offshore pipelines play an important role in the transportation of gas, oil, water and oil products. It is common to have a group of pipelines in the oil and gas field. To reduce the installation cost and time, dual pipelines are designed. There are great advantages in the installation of dual pipelines over two separate single lines. It can greatly reduce the cost for trench, back-filling and installation. However the installation of dual pipelines often requires technical challenges. Pipelines should be placed to be stable against external loadings during installation and design life period. Dual pipelines in trench can reduce the influence of external forces. To investigate the flow patterns and forces as trench depth and slope changes, number of experiments are conducted with PIV(Particle Image Velocimetry) equipment in a Circulating Water Channel. Numerical approaches to simulate experimental conditions are also made to compare with experimental results. The velocity fields around dual pipelines in trench are investigated and analysed. Comparison of both results show similar patterns of flow around pipelines. It is proved that the trench depth contributes significantly on hydrodynamic stability. The trench slope also affects the pipeline stability. The results can be applied in the stability design of dual pipelines in trench section. The complex flow patterns can be effectively linked in the understanding of fluid motions around multi-circular bodies in trench.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.227-234
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• 2002

Laboratory experiments were conducted to examine the behavior of metalaxyl in environment which was used as pesticide in green soil of golf course and as functions of the characteristics of adsorption, desorption and degradation in soil texture and organic matter contents. Acid water containing metalaxyl was conducted to evaluate the effects on adsorption, desorption and degradation. The adsorption of metalaxyl played more significant role in organic contents than clay contents, and pH Increases more pH 2.5 than pH 5.6. The desorption of metalaxyl from contaminants soil decreased higher organic contents LS-soil than S-soil, but the desorption amount of metalaxyl increased more pH 5.6 than pH 2.5. The rate of degradation of metalaxyl in green soil environmental increased higher organic contents LS-soil than S-soil and decreased more pH 2.5 than pH 5.6. These results indicated that the behavior of metalaxyl of the green soil was affected the soil texture of the golf course. Increasing of organic contents, the adsorption amount of metalaxyl on soil increased. Moreover the decrease of the pH of solution increased adsorption amounts and decreased desorption amounts. As the results, the transportation of metalaxyl in soil decreased the acidic rates. The acidification of soil by the acid rain increased the adsorption amount of metalaxyl, but the degradation of metalaxyl decreased. Therefore, it is possible to sustain contamination in run-off the stream and ground water by residuals in soil.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.79-82
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• 2003

An aquaculture system for feeding the caged fishes in the open water is suggested for ocean application. Survival and operation conditions are defined at the conceptual design. Wave and current drag forces are discussed to determine the proper dimension of the aquaculture system and the related mooring system. Second order wave drift force at the survival condition is the dominant force, which be reduced by minimizing the superstructure open to the surface. Automation in feeding, sorting, cleaning is introduced to use the ongoing technology for quality product. The suggested system has advantage compared to onshore culturing, but not to shallow water culturing system. There is room for real application in future by the countries, such as Korea and Japan, which are in short of fish supply and have willingness to venture towards the ocean aquaculture.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.47-52
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• 2010

The wave energy absorption efficiency and the first-order and the time-mean second-order wave loads of a three-dimensional bottom-mounted oscillating water column (OWC) chamber structure are studied. The potential problem is solved by making use of a hybrid Green integral equation associated with the finite-waterdepth free-surface Green function outside a twin chamber and the Rankine Green function inside taking account of the fluctuating air pressure inside the chamber. Numerical results of the primary wave energy converting efficiency and the oscillating and steady wave loads of a three-dimensional bottom-mounted OWC pilot plant have been presented.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.423-428
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• 2007

The 21st century is that both human and environment live together. The advancing knowledge concerning our environment instigates a change in understanding about the physical surroundings. The construction field particularly induces significant improvements that are environmental-friendly. To convene this demand, several manuals and guidelines related to the environmental issues have been enacted and amended. Especially the manuals and guidelines issued from Ministry of Environment (MOC) and Ministry of Construction and Transportation (MOCT) is requiring the addition of environmental knowledge in construction technology. Recently, environmental assessments and advanced environmental measures in various kinds of construction are persuasively been carried out. The policy of Total Maximum Daily Load is the one more reason for the revisions of the manual and guideline, which is really requiring the addition of the environmental knowledge in construction technology. Therefore, this research is focusing on revising the manuals and guidelines related to road construction and maintenance works issued from MOCT.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.123-128
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• 2011

It has been stand high in estimation to converse from Carbon dioxide to Dimethyl Ether in new alternative fuel energy division in 21C, especially Using of DME in point of view of transportation fuel has been discussed of a new clean energy which is very lower of exhaust gas than gasoline and diesel energy. In this paper it is used ZSM-5 and I developed new catalyst by addition of cerium to control acidity. The new catalyst was proved high conversion rate, when it was conversed from methanol to DME, there wasn't any additional material except DME and water, and I overlooked reaction temperature, reaction time, amount of catalyst, amount of added cerium, effect of water content in methanol, reaction temperature by making change of reaction time. I have conclude that conversion rate to DME was increased as increased of catalyst amounts. The best catalyst condition of without additional product was treated poisoning from ZSM-5 to 5% cerium and new catalyst was not effected in purity of fuel methanol.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.207-207
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• 2015

지표수 수자원은 다른 형태의 수자원에 비하여 경제성은 우수하나 환경 훼손, 시공간적 변동성에 대한 취약성, 각종 수질 위협요소에 노출되는 단점 을 가지고 있다. 지표수 수자원과는 달리 Aquifer Storage Transportation and Recovery (ASTR) System을 이용한 지하저수지는 수자원의 안전한 확보, 환경문제 등의 측면에서 새로운 대안으로 제시되고 있다. '청정지하저수지연구단'에서 연구하고 있는 '대규모청정지하저수지'는 피압대수층에 담수를 주입하여 형성된 담수체를 수자원으로 이용한다. 본 연구는 피압대수층 주입정 및 양수정 운영에 따른 지반영향을 연구하였다. 과거 지반변형을 고려하지 않은 무분별한 피압대수층의 지하수 개발로 태국, 중국 등지에서 심각한 지반침하를 야기하였으며 이에 대한 대책으로 인공함양이 이루어진바 있다. 피압대수층 상부에 위치한 점토층은 지반변형에 가장 큰 영향을 미치며 점토층의 변형 혹은 파괴 시 지하수 이용 및 인간의 활동에도 영향을 끼칠 수가 있다. 본 연구의 목적은 주입 및 양수가 점토층에 미치는 영향을 분석하고 지반변형을 허용 범위 내로 국한시키기 위해서 피압대수층에 가할 수 있는 최대 수위변화량을 산정하는 데 있다. 양수로 수두가 감소하는 경우 유효응력 증가에 따른 지반침하가 우려되며, 주입으로 수두가 상승하는 경우 지반파괴가 야기될 수 있다.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.621-631
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• 2017

Many developing countries considering the introduction of nuclear power find that large-scale reactor plants in the range of 1,000 MWe to 1,600 MWe are not grid appropriate for their current circumstance. By contrast, small modular reactors are generally too small to make significant contributions toward rapidly growing electricity demand and to date have not been demonstrated. This paper proposes a radically simplified re-design for the nuclear steam cycle for a medium-sized reactor plant in the range of 600 MWe. Historically, balance of plant designs for units of this size have emphasized reliability and efficiency. It will be demonstrated here that advances over the past 50 years in component design, materials, and fabrication techniques allow both of these goals to be met with a less complex design. A disciplined approach to reduce component count will result in substantial benefits in the life cycle cost of the units. Specifically, fabrication, transportation, construction, operations, and maintenance costs and expenses can all see significant reductions. In addition, the design described here can also be expected to significantly reduce both construction duration and operational requirements for maintenance and inspections.