• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.05a
• /
• pp.66-74
• /
• 1999

일반적으로 압출용 빌렛트제조에는 빌렛트상하의 품질변화로 수평연속주조법이 사용되지 않고 있지만 전자기교반법을 이용할 경우 이러한 단점이 없어진다. 따라서 전자기교반장치를 설치한 수평연속주조장치를 이용하여 연주빌렛트를 제조하였다. 최대자속밀도가 1000Gauss 인 전자기교반장치를 설계 제작하였으며, 간접냉각방식의 흑연몰드에서 알루미늄합금을 사용하여 건전한 연주빌렛트를 제조할 수 있는 여러 공정조건을 조사 검토하여 직경 70mm의 기포가 없고 표면이 미려한 등축정을 가진 연주빌렛트를 제조하였다. 인출속도에 따른 수평 연속주조 빌렛트의 표면, 용탕유동라인 및 조직을 검토한 결과 평균인출속도 20mm/min에서 40mm/min까지 아주 미려한 표면특성을 가졌으며, 인출속도가 빠르면 유동라인이 표면에서 중심 쪽으로 완만한 기울기를 가지게 되어 표면응고층이 얇아져 빌렛트가 고액계면에서 끊어지게 되며, 조직미세화는 인출속도가 클수록 미세화되었으나, 결정구상화정도는 인출속도가 빠를수록 악화되었다.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.10
• /
• pp.121-129
• /
• 2006

Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.85-88
• /
• 2000

This paper is dealt with the ways of the improvement of the surface glossing of exposed concrete through the construction field test. The field applied in this test is located at Daechon, Chungnam province where the service training institute of Chongju university has been built. The flowing method is applied. According to the test results, as water to cement ratio, or slump increase after flowed, surface glossing tends to be improved. As for the effects of the forms typer, following orders, which is shown to be better surface glossing values, are given; Acryle > fancy wood forms > steel forms > plywood forms.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2001.11a
• /
• pp.28-33
• /
• 2001

This paper presents the results of mock up test on the manufacturing of high fluidity concrete by applying flowing methods with segregation reducing type superplasticizer(SRS). Three kinds of mock up structure are made such as. conventional concrete(A), high fluidity concrete(B) and high fluidity concrete incorporating 20% of fly ash(C). Physical and mechanical properties, temperature history of structure and nondestructive test are performed. Segregation reducing type superplasticizer is put into base concrete at field, and base concrete is also flowed at field. C mock up structure which requires 0.85% of SRS to flow base concrete shows most desirable performance at fresh state. The highest rising temperature shows the lowest at C structure among the tested structures. Strength variations before and after flowing also show the lowest values at C structures.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.9
• /
• pp.4310-4318
• /
• 2012

The case study house program has been researched as an example of residential architecture exhibition which represents the industrialized modernism influenced by europe architecture for having characteristics of modular system for mass production, technical experiments and universal space. This study analyzes the case study houses from a localized modernism point of view and defines the characteristics of them as various refracted site plan, intergrated interior and exterior space and various regional material use.

• Journal of Aquaculture
• /
• v.7 no.3
• /
• pp.177-187
• /
• 1994

The objective of the present study were to evaluate nitrification characteristics and determine optimum treatment conditions of three phase fluidized bed reactor for recycling water treatment of aquaculture. When the loading rates were 2.739-0.086kg $COD/m^3/day$ and 1.575-0.128kg $NH_4\;^+-N/m^3/day$, COD and ammonia removal efficiencies were $56.3-94.7\%\;and\; 67.3­92.6\%$, respectively. The maximum removal rates of COD and ammonia were 1200mg/l/day and 488mg/l/day, respectively. Ammonia removal rates were more than $90\%$ beyond 1hr HRT. The ammoniaremoval efficiency was sensitive to the variation of media concentration and air flowrate.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.20 no.3
• /
• pp.27-33
• /
• 2012

According to the statistics of the Ministry of Environment, the emission of sewage sludge is increased by 7~9% yearly. In the future, it will be increased continuously because of extension of sewage disposal plants, high class treatment for removing nitrogen and phosphorus. Until now, we have depended on reclamation for lots of quantity and some part has been treated by ocean emission. But, direct reclamation of organic waste will be prohibited and even ocean emission will be prohibited now, so the treatment of sludge is put on emergency alert. Bio-gas can be produced by applying anaerobic digestion method for the recycling or refuse derived fuel can be conducted by applying carbonization method. However, the process is difficult, causes bad smell and makes it the second waste, so it cannot be practical method in fact. This study applied a fluidized bed combustor for sewage sludge treatment technologies that can actually take advantage of key technologies in order to verify its purpose is to demonstrate selected. If applying the fluidized bed combustor, it can be easily utilized as the replaced resource of energy(fuel) in the countries whose energy resources are insufficient, like our country. Especially, if applying only original strengths of the fluidized bed combustor sufficiently, the sewage sludge can be treated simply, eco-friendly, sanitarily and economically. Particularly, it is verified as the energy technology suitable for government's green growth policy.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.81-82
• /
• 2010

As a part of rapid construction technology of bridge pier caps, controversial issues for design and construction of precast pier caps were discussed. Three kinds of approaches of rapid bridge pier cap construction were proposed and discussed. Especially for an approach of precast shell type structures, experimental studies were performed to evaluate structural performance and compared with conventionally constructed reinforced concrete pier cap.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1A
• /
• pp.155-163
• /
• 2008

On the construction site with trends of large scale, high rise and specialization, testing construction of high performance concrete, superior to conventional concrete, is continued to increase. For bridge construction, application of full staging method is gradually decreasing due to noise, dust, and prolonged construction period. Recently, precast construction, which is optimized to urban environment and shorter work period, gains popularity significantly. In bridge structure, overcrowding arrangement of bar is used to ensure its safety. For the manufacturing of overcrowding arrangement of bar, High flowing self-compacting concrete, which is superior to conventional concrete in flowability and compacting property, should be implemented. In this study, the application of blast-furnace slag and fly ash to binary and ternary blended system on the High flowing self-compacting concrete for bridge structure with overcrowding arrangement of bar is evaluated by flowability in accordance with the first class regulations of Japan Society of Civil Engineering (JSCE).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.5
• /
• pp.868-873
• /
• 1997

Nitrifier consortium entrapped in Ca and Ba-alginate beads were packed into two reactors and studied for removing ammonia-nitrogen in aquaculture system. The ammonia-nitrogen concentration of the influent was continually kept about 2 ppm. At the hydraulic residence time of 0.6 hours, ammonia-nitrogen removal amount of two reactors was about 52.6 and 51.0 g $NH_3-N/m^3/day$, respectively. The ability of adjusting to an impulsive leading which was happened according to variations of HRT was better at Ba-alginate reactor, but its discrepancy was not so large. At the respect of removing ammonium-nitrogen, two reactors showed the similar ability of treating recirculating water.