• 폴리머
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• 제25권6호
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• pp.774-781
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• 2001

폐타이어와 폐석분 재활용을 위하여, 불포화 폴리에스터 수지에 폐석분과 폐타이어 분말의 충전량을 변화시켜 폐타이어-폐석분/폴리에스터 혼성 복합재료를 제조하였다. 매트릭스 내에서 충전제의 계면결합력과 분산력을 향상시키기 위하여 실란 커플링제[${\gamma}$-methacryloxy propyl trimethoxy silane(${\gamma}$-MPS)]를 사용하여 표면처리하고 복합재를 제조한 후 구조와 물성을 확인하였다. 실란 커플링제로 충전제를 표면처리한 경우 초기 열분해온도가 상승하고 중량감소율이 감소하였다. 커플링제로 표면처리된 경우 높은 기계적 물성을 얻었으며, 실란 농도 2 wt%에서 매트릭스 및 WTC의 함량에 관계없이 최대값을 나타내었다. 유기 충전제 증가에 따라 복합재의 기공도는 증가하나 표면처리에 의해 감소시킬 수 있으며 유기 충전제의 함량에 따라 기공 크기분포도 변화한다.

• 멤브레인
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• 제25권4호
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• pp.358-366
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• 2015

강도가 강하고 내약품성, 무독성, 내연소성의 장점을 가지고 있는 PVdF (polyvinylidene fluoride) 나노섬유로 기공이 $0.4{\mu}m$ 평막을 제조한 후, 그 평막으로 부직포를 첨가하여 나권형 모듈을 제작하였다. 카올린과 휴믹산으로 조제한 모사용액과 순수를 대상으로 나권형 모듈의 투과선속과 처리율을 비교하여 pH의 영향을 알아보았고, 여과실험 후 물 역세척을 하여 회복률과 여과저항을 계산하였다. 또한, 나권형 모듈을 통과한 처리수를 입상 활성탄(GAC, granular activated carbon)으로 채워진 컬럼에 통과시킨 후, 탁도와 $UV_{254}$ 흡광도를 측정하여 GAC의 흡착 효과를 고찰하였다.

• Carbon letters
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• 제13권2호
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• pp.109-114
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• 2012

A nuclear, biological, chemical (NBC) canister was indigenously developed using active carbon impregnated with ammoniacal salts of copper (II), chromium (VI) and silver (I), and high efficiency particulate aerosol filter media. The NBC canister was evaluated against carbon tetra chloride ($CCl_4$) vapours, which were used as a simulant for persistent chemical warfare agents under dynamic conditions for testing breakthrough times of canisters of gas masks in the National Approval Test of Respirators. The effects of $CCl_4$ concentration, test flow rate, temperature, and relative humidity (RH) on the breakthrough time of the NBC canister against $CCl_4$ vapour were also studied. The impregnated carbon that filled the NBC canister was characterized for surface area and pore volume by $N_2$ adsorption-desorption isotherm at liquid nitrogen temperature. The study clearly indicated that the NBC canister provides adequate protection against $CCl_4$ vapours. The breakthrough time decreased with the increase of the $CCl_4$ concentration and flow rate. The variation in temperature and RH did not significantly affect the breakthrough behaviour of the NBC canister at high vapour concentration of $CCl_4$, whereas the breakthrough time of the NBC canister was reduced by an increase of RH at low $CCl_4$ vapour concentration.

• 한국세라믹학회지
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• 제46권6호
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• pp.602-608
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• 2009

The yield is increasing as the manufacturing technology of ceramics progresses, however, there are many ceramics of poor quality due to variables upon producing ceramics. Some of those waste ceramics are recycled by sanitary ware or tile manufacturers, but most of them are filled in making environmental problem. Therefore, a research begins to recycle waste ceramic ware as alternative to some imported ceramic ware materials and to reduce environmental pollution. This study, succeeding last study which applied waste white ware as ceramic body material, aimed to solve problems of environment and materials by recycling waste ceradon generated in specially formed areas for ceramic in Gyeonggi-do such as Icheon, Yeoju and Gwangju as the ceramic body material. Consequently, the addition of waste ceramic ware into the ceramic body was judged to have limit up to 30% according to plasticity measurement. As we added shredded waste ceramic ware as much as 30% into basic ceramic body and checked its features, the pore rate and absorption rate were good to be average 4% and 3% respectively. In addition, it showed strength more than 720 kgf/$cm^2$ which is higher than existing ceradon body on the market with good sinter state; so it is judged to be available or developed as new ceramic body.

• 한국대기환경학회지
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• 제20권6호
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• pp.749-758
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• 2004

Nitrous oxide ($N_2$O) has been known as an important trace gas due to the greenhouse gas and the major source of stratospheric oxide of nitrogen (NO). Soil is the major source of $N_2$O in nature. The physicochemical characteristics of soils affect the emission of $N_2$O from soil. These physicochemical parameters are soil moisture, soil temperature, and soil N content. Since these parameters are correlated to the flux of $N_2$O from soil individually and compositely, there still remain many unknowns in the mechanism to produce $N_2$O in soil and the roles of such physicochemical parameters which affect the soil $N_2$O emission. Soil $N_2$O fluxes were measured at different levels in water filled pore space (WFPS), soil temperature and soil N contents from the same amounts of soils which were sampled from agriculturally managed upland field in a depth of ～30 cm at Kunsan. The soil $N_2$O flux measurements were conducted in a laboratory with a closed flux chamber system. The optimum soil moisture and soil temperature were observed at 60% of WFPS and ～13$^{\circ}C$. The soil $N_2$O flux increased as soil N contents increases during the whole experimental hours (up to 48 hours). However, average $N_2$O flux decreased after ～30 hours when organic carbon was mixed with nitrogen in the sample soils. It is suggested that organic carbon could be important for the emission of $N_2$O, and that the ratio of N to C needs to be identified in the process of $N_2$O soil emission.

• 한국표면공학회지
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• 제45권6호
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• pp.248-256
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• 2012

A Pd-based hydrogen membranes for hydrogen purification and separation need high hydrogen perm-selectivity. The surface roughness of the support is important to coat the pinholes free and thin-film membrane over it. Also, The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced various surface pre-treatment such as alumina powder packing, nickel electro-plating and micro-polishing pre-treatment. Especially, the micro-polishing pretreatment was very effective in roughness leveling off the surface of the porous nickel support, and it almost completely plugged the pores. Fine Ni particles filled surface pinholes with could form open structure at the interface of Pd alloy coating and Ni support by their diffusion to the membrane and resintering. In this study, a $4{\mu}m$ surface pore-free Pd-Cu-Ni ternary alloy membrane on a porous nickel substrate was successfully prepared by micro-polishing, high temperature sputtering and Cu-reflow process. And $H_2$ permeation and $N_2$ leak tests showed that the Pd-Cu-Ni ternary alloy hydrogen membrane achieved both high permeability of $13.2ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ permation flux and infinite selectivity.

• 한국지반환경공학회 논문집
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• 제13권10호
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• pp.85-94
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• 2012

최근의 건설공사는 개발사업의 증가와 국토의 효율적 개발에 의해 인접시설물과의 충분한 이격거리를 확보하지 못하고 공사를 진행하는 경우가 점차 증가하고 있다. 본 연구에서는 초고층빌딩 개발을 위한 지반 굴착공사와 철도시설 공사가 비슷한 시기에 수행된 지역에서 발생한 인접 철도시설물의 피해사례를 소개하고, 지층 특성과의 상호작용을 고려한 효율적인 보수 보강이 시행된 사례를 소개하고자 한다. 이를 위해 철도시설물 시공 시와 초고층빌딩 시공을 위한 굴착 공사 시 각종 현장조사 및 시험들이 수행되었으며, 이를 토대로 철도시설물과 선로의 침하 원인 분석이 시행되었다. 추가적으로 지반의 공극 충진을 통한 지반보강과 철도구조물의 침하복원을 위해 마이크로 시멘트를 적용한 보강 그라우팅 공법이 수행되었다.

• Parasites, Hosts and Diseases
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• 제58권1호
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• pp.87-91
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• 2020

Gymnophallid metacercariae found in the Manila clam Ruditapes philippinarum ('Banjirak' in Korean) from Gochang-gun, Jeollabuk-do, Korea were morphologically and molecularly confirmed to be Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974. The metacercariae were morphologically characterized by having a large oral sucker, small ventral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, which were all compatible with P. duboisi. Some of the metacercariae were experimentally fed to mice, and adult flukes were recovered at day 7 post-infection. The morphology of the adult flukes was basically the same as that of the metacercariae except for the presence of uterine eggs; the uterus was filled with up to 40 eggs. The nucleotide sequences (1,193 bp) from ITS regions (ITS1, 5.8S rDNA, and ITS2) of the metacercariae showed 99.7% identity with P. duboisi and 75.7% identity with Gymnophalloides seoi deposited in GenBank. These results confirmed the presence of P. duboisi metacercariae in the Manila clam R. philippinarum in an estuary region of Gochang-gun, Korea.

• Nuclear Engineering and Technology
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• 제23권4호
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• pp.374-386
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• 1991

시멘트 고화체내 Cs-137의 침출에 영향을 미치는 여러 새로운 인자들에 대해 조사하였다. 조사된 인자들은 가압 상태 및 진동 상태에서의 시멘트 경화, 압력하에서의 침출, 여러 종류의 점토 첨가, 이온 교환 수지(IRN-77)의 첨가, 그리고 $CO_2$또는 공기 주입의 영향이다. 침출실험은 IAEA가 제시한 방법에 의해 수행되었고, 실험 결과를 해석하기 위해 시멘트 고화체에 대한 기공 구조를 BET방법으로 분석했다. 처분장에 처분된 고화 드럼 주위에는 뒷채움재가 채워져 있기 때문에 시멘트 고화체가 직접 지하수와 접촉할 가능성은 매우 희박하다. 그래서 뒷채움재가 침출능에 미치는 영향을 예측하였다. 잘 알려진 확산 이론을 이용하여 뒷채움재를 고려했을 때 Cs-137 또는 비방사능 물질의 장기 침출율과 누적 침출량을 예측하였다.

• Journal of Korean Society for Atmospheric Environment
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• 제14권E호
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• pp.9-17
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• 1998

Oxides of nitrogen play important roles in atmospheric chemistry. Soil has been recognized as a major natural source of NO, and its emission depends on soil parameters such as soil nitrogen availability, soil moisture and temperature. It is necessary to understand effects of these controlling parameters on soil NO emission. In order to understand soil moisture effects on NO emission, variations of NO concentration and existence of its equilibrium concentration were observed from ammonium fertilized Japanese upland soil prepared for different soil moisture conditions. The closed chamber technique was employed for this study. The significant increases in NO with soil moisture were found. Maximum was occurred at sample ID4 (55% of water-filled pore space (WFPS)), but it decreased as soil moisture increased. No significant NO concentration was emitted from soil sample without fertilizer, but there was significant NO in fertilized soil samples. The magnitudes of NO from soil increased with time and reached at steady state within ten minutes approximately. These results suggest that nitrogen input from fertilizer takes charge in the first step of sharp increase in NO emission, and then soil moisture becomes important factor to control NO emission from the soils. NO concentrations from soil were compared to those one-day after the experiment. Results from the comparison analysis suggest that the soil NO flux might have been stimulated by soil disturbances like mixing, and this is much more effective in dry soils rather than in wet soils. It was found that much less NO came out from soils after a day; suggesting that most of NO was released from the soils within a day after fertilizer application during our experiment. The length of NO releasing time span may depend on the amounts of fertilizer applied, soil moisture condition, and other soil physical parameters.