• 한국기계가공학회지
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• 제13권2호
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• pp.81-88
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• 2014

Synthetic products such as casting tape and splints are rapidly replacing conventional plaster casts to treat orthopedic patients. Most synthetic products are produced through a polymerization process with related chemical agents. In this study, the effect of the process parameters on the residual NCO content within a prepolymer for casting tape and the hardening temperature for casting tape were experimentally evaluated. In order to verify the effects of the process parameters, an experimental method was adopted. From an S/N ratio analysis, optimal parameter combinations were determined to produce a pre-polymer with a suitable residual NCO content and alower hardening temperature. Prediction models for the NCO content and the hardening temperature were developed and confirmed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.412-419
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• 2009

Large quantity of extra soils discharged from excavation site in Songdo area can be treated by hardening agents and utilized in surface stabilized layer overlying thick reclaimed soft soil deposit. Though surface layer stabilization method using cement or lime for very soft soils has been studied in recent years, but studies on moderately soft clayey silt has not been tried. The purpose of this research is to investigate optimum mixing condition for stabilizing Songdo marine soil with low plasiticity. The optimum mixing conditions of hardening agents with Songdo soil such as kind of agents, mixing ratio, initial water content and curing time are investigated by uniaxial compression test and laboratory vane test. The results indicate that strength increases with high mixing ratio and long curing time, while decreases drastically under certain water content before mixing. Finally, optimum mixing condition considering economic efficiency and workability with test results was proposed.

• 한국지반환경공학회 논문집
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• 제2권2호
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• pp.59-64
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• 2001

고화재를 이용한 천층혼합처리공법을 적용할 경우, 주행성 확보, 공기의 단축, 치환토부족 문제 해결, 사토로 인한 환경문제해결 등의 장점으로 최근 그 활용가치가 점점 커지고 있다. 본 연구에서는 최적의 천층고화처리를 위하여 국내의 대표적인 3가지 고화재를 이용한 현장토의 실내개량강도 특성을 고화재별, 양생일수별, 함수비별로 분석하였다. 실내시험결과를 토대로 적정 배합비에 따른 현장강도를 추정하여 현장시공 후 개량보강효과를 확인하여, 현장개량강도는 소요설계강도 $5.0kgf/cm^2$이상 확보되었다.

• 한국응용과학기술학회지
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• 제27권4호
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• pp.470-474
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• 2010

Various anti-scattering agents for suppression of dust scattering at waste depository were compared in this study. Based on the price, easy of usage, and no toxicity, 1% of $Al_2(SO_4)_3$ was selected as surface hardening agents. Only lower than 2% of total weight were flied when wind speed was monthly maximum velocity during 1 hr. These results were quite good with comparison of S anti-scattering agents which was made by C company in Korea. When $Al_2(SO_4)_3$ was spread, the surface waste became hard therefore the effect of suppression of scattering dust was long lasting. It was recommend that 2% of $Al_2(SO_4)_3$ was spread to keep suppression of scattering dust when sudden gust of wind such as natural disaster was occurred.

• 한국해양공학회지
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• 제28권2호
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• pp.140-146
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• 2014

This study investigated the engineering characteristics of non-sintering binder-stabilized mixtures consisting of different ratios of a hardening agent(3%, 6%, 9%, 12%) for recycling industrial by-products through several series of laboratory tests. The hardening agents consisted of two kinds of non-sintering binders(NSB-1, NSB-2), which were developed by using inter-chemical reactions among blast furnace slag, phospho-gypsum, and an alkali activator. In addition, ordinary Portland cement(OPC) was used to compare the engineering characteristics of the stabilized mixture. An unconfined compressive test showed that the unconfined compressive strength increased with the curing time and mixing ratio. Experimental test results indicated that the 7-day strength of the NSB-1 mixture was similar to that of the OPC mixture. However, its 28-day strength was higher than that of the OPC mixture. The secant module of elasticity showed a range of $E_{50}=(42-109)q_u$ regardless of the agents. Based on the results of triaxial tests, the cohesion and friction angle increased with the mixing ratio.

• Corrosion Science and Technology
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• 제7권5호
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• pp.269-273
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• 2008

It is known that the fluoric resin has the most outstanding properties in the extremely acidic environment of high temperature. However, this resin is the thermal hardening type that needs long time heat treatments above $250^{\circ}C$. It's impossible to use in situ in the extremely acidic environment such as a huge FGD ductworks or industrial chemical tanks. Furthermore, even the natural hardening type fluoric coatings which can be hardened less than $120^{\circ}C$ can not be applied to the highly acidic environmental plants because of its chemical resistance. In this study, new fluoric coatings that has excellent thermal resistance, chemical resistance and corrosion resistance has been developed in order to solve above problems and to be applied to the large plant structures in the field. These newly developed coatings are organic and inorganic composite type that have fluoric rubber(100 wt%), fluoric resin(5~50 wt%), oxalates(5~30 wt%), inorganic fillers mixed with plate-type and bulk-type solids(20~150 wt%), hardeners(0.5~5 wt%), and hardening hasteners(0.1~3 wt%). The best chemical and physical properties of these coatings are acquired by variation of adhesive reinforcement agents, dispersants, leveling agents. Mixing ratios of plate-type and bulk-type inorganic fillers influence the thermal properties, abrasive resistance and chemical infiltration properties of coatings. The mixing control is also very important to have homogeneous surface and removing inner voids of coatings.

• 복합신소재구조학회 논문집
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• 제6권4호
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• pp.8-15
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• 2015

The demand for environmental consideration is on the increase in civil engineering. This study focuses on the development of technology to reduce the use of carbonate cement and improve its performance by using a silicate mineral and hardening agents, and presents the test results for the demonstrative evaluation of the properties of the raw material. Highly active feldspar was used as a binder to augment the bonding of the carbonate cement, and their change in strength was observed after test piece construction with the addition of soluble hardening agent. The uniaxial compression strength of the test piece of the general Portland cement with the addition of 0.5% soluble hardening agent, showed an increase by 33% and that of the test piece of cement with the addition of 70% substituted with feldspar increased by 28%. The strength of viscous soil; classified as soft ground, showed an increase of a maximum of 1.7 times when it was mixed with cement and solidifier depending on the curing period. These tests confirmed that a soluble solidifier is effective for improving the strength of a cement binder and that the highly active feldspar can be used as a binder.

• Clinical and Experimental Reproductive Medicine
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• 제21권1호
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• pp.99-110
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• 1994

One consequence of fertilization in mammals is an increased resistance of the zona pellucida (ZP) to proteases and various chemical reagents. This phenomenon has been called 'zona pellucida hardening' (ZPH), and it is generally accepted that it is caused by the secretory products of cortical granules released by the egg at fertilization. ZP of mouse oocytes maturing in vitro in a chemically defined medium becomes progressively more resistant to solubilization by chymotrypsin ("Spontaneous" ZP hardening). In the present study, it was aimed to find the specificity of spontaneous ZPH in relation to its possible relevance to the cortical reaction and the physiological block to polyspermy. When a maturation inhibitors, cAMP analog(dbcAMP) and phosphodiesterase inhibitor (IBMX) was added to culture medium, it prevent spontaneous ZPH of mouse oocyte during in vitro culture. Thus spontaneous ZPH requires GVBD, since it is prevented by those agents, which inhibit GVBD in vitro. However, culture for 3 hours in the presence of PMA(lOng/ml), a protein kinase C activator, resulted in ZPH without GVBD, thus suggesting that ZPH may be regulated independently apart from the event of GVBD. Pretreatment of mouse oocyte with FBS result in partially inhibitory effect on subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhibitory effect on the spontaneous ZPH, but subsequent spontaneous ZPH. Induction of GVBD in vivo had a inhinbitory effect on the spontaneous ZPII, but had no inhibitory effect on PMA-induced ZPH. Treatment with a microfilament formation blocker(cytochalasin-B) at 1${\mu}g$/ml concentration, resulted in the excellent inhibitory effect on spontaneous ZPH. However cytochalasin-B did not inhibit PMA-induced ZPH. Thus this suggesting that spontaneuse ZPH had a different mechanism from PMA-induced ZPH.

• 한국응용과학기술학회지
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• 제16권2호
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• pp.179-185
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• 1999

본 연구에서는 연질 폴리우레탄 발포제 제조에서 여러 발포제와 내부온도, 기계적 물성과의 관계에 대해서 연구, 조사하였다. 발포제로는 물을 주발포제로 하여 보조발포제는 CFC-11(trichlorofluoromethane), HCFC-114b(dichlorofluoroethane), dichloromethane, n-pentane, iso-pentane, cyclopentane을 사용하였다. 기계적 물성을 측정하기 위하여 연질 폴리우레탄 발포제의 밀도가 $0.015{\pm}0.002g/cm^3$와 $0.024{\pm}0.002g/cm^3$인 두 종류의 발포제를 제조하였다. 연질 폴리우레탄의 발포제의 제조시 발포제별로 내부온도를 측정하였으며, 48시간 경과 후 밀도, 인장강도, 신장율, 인열강도, 압축강도, 압축영구변형률을 측정하였다. 연구 결과 dichloromethane과 cyclopentane이 보조발포제로 가장 적합하였다.

• 한국지반환경공학회 논문집
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• 제11권1호
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• pp.53-59
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• 2010

해수 침적 조건에서 시멘트 수화물이 부식되는 화학적 열화과정은 콘크리트 구조물이나 주입공사 목적물에서 동일하다. 국내에서 사용되고 있는 MSG(Micro Silica Grouting)주입재는 실리카질 물질이 다량 함유된 혼합계 시멘트로서 분말도가 $8,000cm^2/g$ 이상으로 높기 때문에 수화활성도가 매우 크고, 고강도 및 고내구성을 특징으로 하며, $C_3A$ 함유량도 5% 이하로 내황산염시멘트 규격을 만족하는 내해수성 시멘트재로 평가된다. 따라서, 본 논문에서는 내해수성이 우수한 MSG와 국내에서 사용되고 있는 급결재를 조합하여 내해수성 특성을 실험적으로 평가하였다. 국내에서 일반적으로 규산계 고활성 급결재 또는 초속경시멘트계 무기질 급결재가 사용되고 있다. 이들 급결재와 MSG가 조합된 주입재의 호모겔 시편에 대해서 압축강도, 중량변화 및 길이변화 특성을 실험적으로 평가하여 내해수성이 우수한 주입재 조합을 제시하였다.