• 한국대기환경학회지
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• 제24권1호
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• pp.55-62
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• 2008

This study is aimed at substantially reducing the particulate matter (dust) emission during the combustion of heavy fuel in boilers by addition of combustion improver. The combustion improver used were the oil-soluble organometallic compounds that were found to be more effective than the dispersing agents that are generally used for reducing the particulate emission. The dust reduction effect was found to depend on the active materials (metals) as well as on the organic ligand part of organometallic compounds. Acetylacetonoate and naphthenate of Fe and Ca were found to be most effective for dust reduction. Addition of Fe and Ca organometallic compounds as combustion improver in concentration of 30 ppm (metal basis) to heavy fuel oil, caused dust reduction by 50 wt% to 80 wt%.

• 한국주조공학회지
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• 제14권3호
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• pp.240-247
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• 1994

TiC particulate reinforced magnesium matrix composites were fabricated by melt stirring method. The effect of alloying elements on TiC particulate dispersion into molten magnesium and mechanical properties were investigated. The incorporation time is defined as the time required for dispersion of solid particles into molten metal. The incorporation time of TiC particles into molten pure magnesium was remarkably shorter and the particulated dispersion was more uniform than that of pure aluminum which was reported previously. The incorporation time was, prolonged by the addition of Al, Bi, Ca, Ce, Pb, Sn or Zn. The tensile strength increased and elongation decreased by the addition of Cu or Sn into the matrices and composites. Although, the tensile strength of the matrices and composites increased by alloying with Ca or Ce, the maximum elongation was observed at a content of about 1% for the matrices. By alloying with Zn, the tensile strength increased for the matrices and composites, but the elongation of the matrices increased. The pure magnesium and its alloy matrix composites reinforced with 20vol% TiC have the tensile strength of about 400MPa. This value is compared with the tensile strength of SiC whisker reinforced magnesium matrix composites fabricated by liquid infiltration method at the same volume fraction. There fore, the melt strirring method which has the advantages of simple process is considered to be efficient in fabricating magnesium matrix composites.

• 대한기계학회논문집B
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• 제39권4호
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• pp.351-358
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• 2015

세계적인 배출가스 규제의 강화와 함께 화석 연료의 매장량 감소와 유가 상승은 새로운 엔진 기술 개발을 촉진시켰다. 가솔린 직접 분사(GDI; Gasoline Direct Injection) 엔진은 연료를 직접 연소실에 공급하고 정밀한 연소제어를 통해 공연비가 희박한 혼합 상태에서도 연소가 가능하게 하였는데, 이러한 방식은 기존 포트 분사 엔진보다 연비와 출력을 모두 향상시킬 수 있다. 하지만 GDI엔진은 디젤 엔진의 경우와 마찬가지로 soot 발생률이 높아짐에 따라 입자상 물질의 배출이 증대되는 문제를 안고 있다. 이러한 문제를 해소하고자 본 연구에서는 가솔린 입자상 물질 필터(GPF; Gasoline Particulate Filter)를 개발하여 입자상 물질의 배출정도를 저감시키고자 하였다. 필터의 설계 효율에 따라 3가지의 Metal foam 필터와 단일 Metal fiber 필터를 실험에 적용하여 PM과 PN의 저감률을 비교하였다.

• 한국약용작물학회지
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• 제14권3호
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• pp.130-133
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• 2006

더덕 종자의 파종시 산파에 의한 종자 손실이 클 뿐만 아니라 입모 후 잡초 발생에 의한 제초 관리가 어려워 재배 농가에서 어려움이 많아 발아 미세환경을 개선시킬 수 있을 뿐만 아니라 기계화 점파 및 멀칭 재배가 가능하고 제초문제를 해결할 수 있는 더덕 종자 펠렛팅 연구를 실시하였던 바 그 결과를 요약하면 다음과 같다. 다양한 피복물질을 이용한 펠렛팅 종자의 발아율은 PID처리가 가장 높았으며 Illite, PIT, Diatomite, BT 순으로 높게 나타났다. 접착물질은 PVP 처리가 가장 발아율이 높았으며 PVA, XG, CMC, AG 순으로 높게 나타났다. 펠렛팅 종자의 피복소재별 성형율, 강도는 PID 가 가장 좋았으며, 발아율에 가장 좋은 물리적 특성은 수분 접촉시 split형의 1/2 균열이 생기고 수분 흡수력은 S자형의 흡수 양상을 보였다. 토양함수량에 따른 발아율은 50% 조건에서 PID처리가 가장 좋았으며, 수분함수량이 높을수록 펠렛팅 종자의 발아율은 증가되는 경향이었다.

• 비파괴검사학회지
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• 제13권4호
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• pp.9-17
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• 1994

초음파법은 종래의 금속재료는 물론 최근의 금속 복합재료등과 같은 신소재의 재료특성을 비파괴적으로 평가할 수 있는 일반적인 방법이다. 그러나 이와같은 재료들의 비파괴 특성 평가를 위해 초음파법을 적용시킬 경우 무엇보다도 재료 내부를 전파하는 탄성파의 전파특성에 대한 물리적 현상에 대한 이해가 필수적이다. 본 연구에서는 금속 복합재료의 제조공정에서 일반적으로 많이 발생되는 기지재와 강화재 사이의 계면 문제 및 기지재에 분포하는 강화재의 체적함유율의 변화등에 의한 유효 평면파의 다중 산란 특성을 SiC 입자강화 6061 알루미늄 복합재료에 대해 Lax의 준 결정 근사(quasi-crystalline approximation) 이론 및 소감정리 (extinction theorem)를 기초로 하여 이론적으로 해석하였다. 그 결과 SiC 입자 강화재의 체적 함유율의 변화에 대한 유효 평면파의 위상속도 및 감쇠의 주파수 의존 특성과 금속복합재료에 있어서의 기지재와 강화재 사이의 계면층의 탄성특성에 대한 위상속도의 변화 특성이 명확하게 규명되었다.

• Journal of the korean society of oceanography
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• 제31권2호
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• pp.55-63
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• 1996

Distribution of suspended particulate matter, dissolved oxygen and major inorganic nutrients along a meridional section ($126^{\circ}$ 33' E) in the Cheju Strait is described along with the hydrographic and current data obtained during April 25-27, 1995. The current measurements was conducted using a vessel-mounted Acoustic Doppler Current Profiler (ADCP). Repeated coverage along an ADCP transect during 25 hours allows to calculate the daily mean along- and cross-strait currents. Measured material concentrations and the mean current speed were used to estimate the flux density (cencentration times current speed) of materials. Two types of depth distibution of flux densities were observed. for nitrate and suspended particulate matter, the depth distribution pattern of materials determines those of flux densities. However, flow patterns determine those of flux densities for dissolved oxygen, phosphate and silicic acid. The total along-strait water volume transport is about 0.3 Sv (1Sv $10^{6}$ $m^{3}/s^{-1}$). The total along-strait material transports are estimated to be 3.1 $${\times} $10^{5}$ $g/s^{-1},$ 2.4 ${\times}$ $10^{6}\;g/s^{-1},$ 7.I ${\times}$ $10^{2}\;mol/s^{-1},$ 3.I ${\times}$ $10\;mol/s^{-1},$ 1.7 ${\times}$ $10^{3}\;mol/s^{-1}$ for suspended particulate matter, dissolved oxygen, nitrate ion, silicic acid and phosphate ion, respectively.

• 한국분말재료학회지
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• 제30권5호
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• pp.415-423
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• 2023

With the increasing attention to environmental pollution caused by particulate matter globally, the automotive industry has also become increasingly interested in particulate matter, especially particulate matter generated by automobile brake systems. Here, we designed a coating composition and analyzed its mechanical properties to reduce particulate matter generated by brake systems during braking of vehicles. We designed a composition to check the mechanical properties change by adding Cr₃C₂ and YSZ to the WC-Ni-Cr composite composition. Based on the designed composition, coating samples were manufactured, and the coating properties were analyzed by Vickers hardness and ball-on-disk tests. As a result of the experiments, we found that the hardness and friction coefficient of the coating increased as the amount of Cr₃C₂ added decreased. Furthermore, we found that the hardness of the coating layer decreased when YSZ was added at 20vol%, but the friction coefficient was higher than the composition with Cr₃C₂ addition.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1995년도 추계 학술발표 강연 및 논문개요집
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• pp.119-119
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• 1995

• 한국세라믹학회지
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• 제45권9호
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• pp.497-506
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• 2008

The long time of twenty years has passed since Diesel Particulate Filter (DPF) was proposed before the practical use. The main factors that DPF has been put to practical use in this time, are the same time proposal of the evaluation method of SiC porous materials linked to he performance on the vehicle, and that the nature of thermal shock required for the soot regeneration (combustion of soot) in the DPF is different from the conventional requirement for the rather rapid thermal shock. For the requirements, these includ demonstrating utmost the characteristic of SiC's high thermal conductivity, and overcoming the difficulty of thermal expansion of SiC-DPF by dividing the filter into segments binding with the cement of lower Young's modulus, and the innovation of technology around the diesel exhaust system such as Common-Rail system. As the results of these, the cumulative shipments of SiC-DPF have reached about 5 million, and it goes at no claim in the market.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.370-371
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• 2006

The particulate strengthened $Cu-MoSi_2$ composites were prepared by a PM process to develop novel copper based composites with reasonable strength, high thermal conductivity and low thermal expansion coefficient. Microstructure of the composites was investigated by SEM; the tensile strength, elongation, thermal conductivity and thermal expansion coefficient (CTE) of the composites were examined. A comparative analysis of mechanical and thermal properties of various Cu-matrix composites currently in use was given and the strengthening mechanisms for the $Cu-MoSi_2$ composites were discussed.