• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.89-96
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• 1995

본 연구는 시멘트 경화체 중의 Cl 고정화 메카니즘을 규명하는 연구의 일환으로 시멘트의 C3A 함유량에 따른 Cl 고정화 효과를 세공용액 분석방법에 의해 조사한 것으로 C3A함유량 0.46 9.65%의 4가지 시멘트와 C3A를 함유하지 않은 초속경 시멘트 페이스트를 밀봉용기내에서 양생시켜 재령 28일에 세공용액을 추출하여 세공용액 중의 Cl 과 OH 농도를 측정, C3A함유량이 Cl 고정화에 미치는 영향을 검토한 것이다. 연구결과 세공용액 중의 Cl 농도는 NaCl 혼입량에 관계없이 시멘트 중의 C3A량이 증가함에 따라 낮아져 시멘트 경화체 내에서 Cl 의 고정화에 C3A가 매우 효과적임을 알 수 있었다. 세공용액의 Cl /OH 는 Cl 혼입량이 시멘트 중량의 0.3%인 경우 강재부동태막을 파괴하는 0.3보다 낮았으며 X선회절분석에 의해 C3A에 의한 고정화 메카니즘은 프리델씨염(Friedel's salt)의 생성에 의함을 확인하였다.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.100-109
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• 2002

Significant damage to concrete results from the intrusion of corrosive solutions, for example, dissolved chlorides corrode reinforcing steel and cause spatting. Effectively blocks the penetration of these solutions will eliminate or greatly reduce this damage and lead to increased durability. This study is to investigate the effects of pozzolanic admixtures, fly ash and silica fume, and a blast furnace slag on the chloride ion penetration of concretes. The main experimental variables wore the water-cementitious material ratios, the types and amount of admixtures, and the curing time. And it is tested for the porosity and pore size distributions of cement paste, chloride ion permeability based on electrical conductance, and 180-day ponding test for chloride intrusion. The results show that the resistance of concrete to the penetration of chloride ions increases as the w/c was decreased, and the increasing of curing time. Also, concrete with pozzolans exhibited higher resistance to chloride ion penetration than the plain concrete. The significant reduction in chloride ion permeability(charge passed) of concrete with pozzolans due to formation of a discontinuous macro-pore system which inhibits flow. It is shown that there is a relationship between chloride ion permeability and depth of chloride ion penetration of concrete, based on the pore structure (porosity and pore size distributions) of cement paste.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.125-132
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• 2006

Recently, surface finishing and protection materials were developed to restore performance of the deteriorated concrete and inhibiting corrosion of the reinforcing-bar. For this purpose, surface protection agent as well as coatings are used. Coatings have the advantage of low Permeability of $CO_2,\;SO_2$ and water. However, for coatings such as epoxy, urethane and acryl, long-term adhesive strength is reduced and the formed membrane of those is blistered by various causes. Also when organic coatings are applied to the wet surface of concrete, those have a problem with adhesion. On the other hand, surface protection agent penetrates into pore structure in concrete through capillary and cm make a dense micro structure in concrete as a result of filling effect. Furthermore, the chemical reaction between silicate from surface protection agent and cement hydrates can also make a additional hydration product which is ideally compatible with concrete body. The aim of this study is to examine the effect of penetrative surface protection agent(SPA) by evaluating several concrete durability characteristics. The results show that the concrete penetrated surface protection agent exhibited higher durability characteristics for instance, carbonation velocity coefficient, resistance to chemical attack and chloride ion penetration than the plain concrete. These results due to formation of a discontinuous macro-pore system which inhibits deterioration factors of concrete by changed the pore structure(porosity and pore size distributions) of the concrete penetrated surface protection agent.

• Clean Technology
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• v.12 no.4
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• pp.224-231
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• 2006

Collection efficiencies and pressure drops for the removal of small particles from dilute liquid suspensions by granular bed filter were calculated using network model. The network model is composed of a number of nodes connected with cylindrical bond and particles are deposited on the bond surface. The collection efficiency of each cylindrical bond was predicted using unit cell model corresponding to the pore volume of cylindrical pore both at the initial and transient states. Deposited particles on the collector surface may act as additional collector and reduce the pore size of the collector. As a result, the collection efficiency was improved and pressure drop increased with deposition. Even though the stochastic nature of network requires a large number of simulation work, the model proposed in this study can be used in investigating collection efficiency and pressure drop.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.515-520
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• 2007

Recently, the treat of sludge is usually progressed by ocean disposal. But it will be totally banned by content of its heavy metal according to London Dumping Convention, gradually. The stable way of treat of sewage sludge should be examined urgently. To solve the problem, recently, there are efficient and environment-oriented method. One of them is to produce absorbent through the activation. This study produces absorbent through steam activation. As basic experiment, optimum activation condition for preparation of good absorbent is researched through study of the fellowing variables : steam flow rate, activated temperature, activation time. As the result of this with standard on iodine adsorptivity, it is chosen, that steam flow rate "30 mL/hr", activation temperature $"500^{\circ}C"$, activation time "60 minutes". At the time, iodine adsorptivity and yield shown that 228.4 mg/g, 77.23%. And also, by using nitrogen adsorption, SEM and EDS are confirmed that pore development, specific surface area, mean pore size, chemical component and content. Pore developed by steam activation is also confirmed that it is micropore.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.120-127
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• 2011

For the development of the environment-friendly insulating composite materials, natural cellulose (wood chip and sawdust) was used as a core material and activated Hwangtoh was used as a binder. Various specimens were prepared with the water/binder ratio and natural cellulose/binder ratio. The physical properties of these specimens were then investigated through compressive and flexural strength test, absorption test, hot water resistance test, thermal conductivity, measurement of pore distribution and observation of micro-structures using scanning electron microscope (SEM). Results showed that the absorption ratio increased with the increase of natural cellulose/binder ratio but decreased remarkably with the increase of polymer/binder ratio. The compressive and flexural strength development varied appreciably with the increase of water/binder ratio and natural cellulose/binder ratio. On the other hand, thermal conductivity decreased with the increase of natural cellulose/binder ratio and polymer/binder ratio. Through SEM, it was found that activated Hwangtoh that reacted with water formed a hydrate crystal leading to the compact structure and the total pore volume of the specimen using activated Hwangtoh was smaller than that of the non-activated Hwangtoh.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.273-279
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• 2003

The purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methylmethacrylate-butyl acrylate(MMA/BA) latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. From the test results, we knew that the pore volume of polymer-modified mortars using MMA/BA latexes at bound MMA contents of 60 and 70 percent is 7.5∼75nm and the fine pore volume is increased with an increase in the polymer-cement ratio. The total pore volume of polymer-modified mortars using MMA/BA latexes is linearly reduced with an increase in the bound MMA content and increased in the polymer-cement ratio. In general, the superior compressive strength of polymer-modified mortars using MMA/BA latexes is obtained at a bound MMA content of 70 percent and a polymer-cement ratio of 15%. And, the water absorption and chloride ion penetration depth are greatly affected by the polymer-cement ratio rather than the bound MMA content. The important factors affecting the properties of polymer-modified mortars using MMA/BA latexes polymerized with various monomer ratios are the variations of the pore size distribution with changing bound MMA content and the polymer-cement ratio.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.7-17
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• 1994

소음이 청기에 미치는 영향에 대해서는 서기 1세기 경부터 그 기록을 더듬을 수 있다. 1713년 Ramazini는 구리 세공자에게 소음을 방지하기 위한 귀 보호기 사용을 권하였으며, 이후 18세기 중엽 산업 혁명을 거쳐 1,2차 세계대전과 함께 20세기의 폭발적인 산업 발달에 맞추어 소음은 문명의 필연적 산물이 되면서 이에 대한 관심이 높아졌다. 우리나라도 경제 발전과 동시에 공장 소음, 자동차 소음등이 날로 심각해지면서 이에 대한 연구가 활발해지고 있으나, 국내외 모두 소음성난청의 치료 면에서는 뚜렷한 방법을 제시하지 못하고 있는 실정이다. 소음에 의한 난청은 일단 한번 발생하면 형태 및 기능이 불가역적이므로 예방만이 유일한 해결책이라고 하겠다.

• Resources Recycling
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• v.10 no.1
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• pp.25-31
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• 2001

The heat treatment of PVC film containing PVC 65ft, DOP (Dioctyl Phthalate) 32% as plasticizer, Ca-Zn stearates and sur-face agent was performed under several conditions to study the dehydrochlorination of PVC and char production. In the case of $H_2$ $SO_4$, the dehydrochlorination was ca.100% at $250^{\circ}C$ for 3h. The char involving the smaller pores was produced with hydro-thermal treatment. The pore size became small with increasing the treatment time and temperature. In the case of treatment with $Ca(OH)_2$, the sizes of pores produced in char were about sever ~10 $\mu\textrm{m}$ at$ 225^{\circ}C$ for 12h. In the case of $_2$$SO_4$, the size of pores were about 1 $\mu\textrm{m}$ in 5M $_H2$$SO_4$for 12h.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.4
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• pp.170-177
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• 2012

Amethyst gems represents thermal effects of far-infrared emission, promotes the body's metabolism, and attracts attention as an eco-friendly interior material. In this paper, amethyst increase the value of jeweling by applying the characteristic purple motif, furthermore, I will intend to develop of design model. Metal crafting of brooch & necklace in the works performed based on the organic three-dimensional shape of the Rhino CAD Data. It was made possible through the precise laminated wax processing and then combining the amethyst. I researched the ornament modeling by applying the 'Golden Ratio', and suggesting utilizing method for interior jewel modeling, and also, is expected that this paper on the amethyst modeling design can contribute to the manufacturers' productivity.