• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.2
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• pp.109-124
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• 2014

In order to understand the carbon cycle in the Amundsen Sea of the Southern Ocean, the export fluxes of particulate organic carbon from the euphotic zone to deep water estimated using ${\psi}$/${\psi}$ disequilibrium method. Seawaters in 14 water columns were collected during February and March 2012, and analyzed for total and dissolved ${\psi}$, and particulate organic carbon. Total ${\psi}$ activities in the water column showed deficiency and excess relative to those of ${\psi}$ depending on the water depth. Deficiency of total ${\psi}$ in the euphotic zone showed mirror images both with chlorophyll-a and fluorescence, and was consistent with the loss of nitrate, which indicated the effect of biological activity. In addition, deficiency of total ${\psi}$ from deep water was associated with the increase of total dissolvable Fe/Mn concentration. Excess total ${\psi}$ activity presented below the euphotic zone might be related to particulate ${\psi}$ concentrated in this water depth. Mean export flux of ${\psi}$ estimated using the steady state model was $867{\pm}246dpmm^{-2}day^{-1}$. Mean export flux of particulate organic carbon, which were estimated by the product of total ${\psi}$ flux and ratio of POC/${\psi}$ ($7.08{\pm}4.27{\mu}molCdpm^{-1}$) in the sinking particles, was $5.9{\pm}3.9mmolCm^{-2}day^{-1}$. These fluxes were similar levels to those in the Weddell Sea during February and March 2008. Export ratios (ThE) relative to the primary production in the euphotic zone were in the range of 3-54% (av. 28%).

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.47-54
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• 2006

Shear wave velocity of uncemented soil can be expressed as the function of effective stresses when capillary phenomena are negligible. However, the terms of effective stresses are divided into the direction of wave propagation and polarization because stress states are generally anisotropy. The shear wave velocities are affected by ${\alpha}$ parameters and ${\beta}$ exponents that are experimentally determined. The ${\beta}$ exponents are controlled by contact effects of particulate materials (sizes, shapes, and structures of particles) and the ${\alpha}$ parameters are changed by contact behaviors among particles, material properties of particles, and type of packing (i.e., void ratio and coordination number). In this study, consolidation tests are performed by using clay, mica and sand specimens. Shear wave velocities are measured during consolidation tests to investigate the stress-induced and inherent anisotropies by using bender elements. Results show the shear wave velocity depends on the stress-induced anisotropy for round particles. Furthermore, the shear wave velocity is dependent on particle alignment under the constant evvective stress. This study suggests that the shear wave velocity and the shear modulus should be carefully estimated and used for the design and construction of geotechnical structures.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.433-434
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• 2003

급속한 산업 발전과 더불어 산업전반에 걸쳐 환경문제가 심각해지면서 생활의 질적 향상에 따른 쾌적 환경을 추구하기 위해 실내와 작업장 내에 떠 있는 먼지나 유해가스 등의 오염물질로 인한 직업성 질병에 대한 관심이 높아지고 있다 실내ㆍ외를 불문하고 환경오염이 인체 건강 및 위생에 미치는 영향은 오염물에 대한 노출시간에 관계하기 때문에 하루의 대부분의 시간을 실내에서 생활하는 현대인에게 실내 환경의 질은 아주 중요하다. 질의 물리적 특성에 따른 가스상, 입자상의 거동 및 농도분포에 대한 수치 해석적 연구는 매우 미흡한 실정이다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.37-38
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• 2001

Polycyclic Aromatic Hydrocarbons(다환방향족 탄화수소류, 이하 PAHs)는 두 개 이상의 벤젠 고리로 구성되어 있는 반휘발성 유기물질로서 가스상과 입자상에 모두 존재한다. PAHs는 주로 불완전 연소에 의해서 생성되며, 주요 고정 오염원은 주거 난방, 코크 산업, 소각이고, 주요 이동오염원은 자동차 엔진이다. PAHs에는 강한 발암성 혹은 돌연변이원성을 가진 화합물들이 포함되어 있고, 주변 대기에 널리 분포되어 있을 가능성이 높기 때문에 일반 대중이 쉽게 노출될 수 있다. (중략)

• Electrical & Electronic Materials
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• v.1 no.3
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• pp.184-196
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• 1988

통칭 particulate media(P.M.)로 일컬어지는 입자형 기록매체는 자성재료가 개개의 particle로 구성되는 자기 기록매체를 말한다. 이 P.M.는 20네기초 정보기록매체로서 steel wire, steel tape이후 등장하여 현재까지 가장 광범위하게 사용되고 있다. P.M.를 포함한 자기 기록매체의 발전사를 요약해 보면 표1과 같다. P.M.중에서도 자기 tape가 차지하는 비중은 절대적이며 특히 viedo tape는 전체 자성체사용량의 약 55%를 점하면서 대량생산에 의한 고품질, 저가격의 장점을 전세계 소비자에게 제공하고 있다. 여기서는 P.M.의 기본물성을 좌우하는 자성체에 대하여 알아보고 P.M.를 품목별로 소개한 다음, P.M.중 가장 많은 생산량을 나타내고 있는 viedo tape의 제조과정을 소개하고자 한다.

• Computational Structural Engineering
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• v.11 no.4
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• pp.267-274
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• 1998

본 연구에서는 기지개와 미시구멍으로 구성된 복합재료에 입자보강 복합재료의 등가 재료상수 예측기법인 평균장 근사이론과 등가원리를 적용하여 위상 최적화에 필요한 등가 재료상수와 설계변수와의 상관관계식을 유도하였다. 또한, 유도된 관계식에 중간값을 갖는 설계변수의 수를 줄이기 위하여 벌칙인자를 도입하였다. 그리고 본 연구의 타당성을 검증하기 위하여 벌칙인자가 도입된 위상 최적화문제를 순차이차계획법인 PLBA 알고리즘을 이용하여 해석하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.577-583
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• 2011

To meet the requirements of the Tier 4 interim regulations for off-road vehicles, emissions of particulate matter (PM) and nitrogen oxides (NOx) must be reduced by 95% and 30%, respectively, compared to current regulations. In this research, both the DPF and HPL EGR systems were investigated, with the aim of decreasing the PM and NOx emissions of a 56-kW off-road vehicle. The results of the experiments show that the DOC-DPF system is very useful for reducing PM emissions. It is also found that the back pressure is acceptable, and the rate of power loss is less than 5%. By applying the HPL EGR system to the diesel engine, the NOx emissions under low- and middle-load conditions are reduced effectively because of the high differential pressure between the turbocharger inlet and the intake manifold. The NOx emissions can be decreased by increasing the EGR rate, but total hydrocarbon (THC) emission increases because of the increased fuel consumption needed to compensate for the power loss caused by EGR and DPF.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.323-335
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• 2020

In this study, a series of site measurement of particulate and gases pollutants at five tunnels were carried out along with case studies to review the suitability of the current road tunnel ventilation design standards. Previous studies by other researchers have shown that the ratios of the level of measurement to the standard were 27.9%, 1.6% and 3.4% for TSP, CO and NOx, respectively. Those measured in this site study shows even lower ratios; the ratios were 2.6%, 0.8% and 0.3%, for TSP, CO and NOx, respectively. The particle size analysis of TSP for the five tunnels shows that PM10 including tire wear and re-suspended road dust exceeded 20.4%. This implies that non-exhaust particulate matter must be taken into account, since the current design standards for the particulate matter (visibility) include only the engine emission. Based on the recent research results, for vehicle emission rate and slope-speed correction factors, revision of ventilation design standards for pollutants is required. WRA (PIARC) also emphasizes the necessity of the ventilation design standards for pollutants. In addition, enactment of a new road tunnel ventilation system operation standard or guideline is strongly recommended when considering the low operating rate of the ventilation system with jet-fans.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.2
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• pp.189-191
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• 2001

Objective : The objective of this study was to determine which forms of iliac cancellous bone grafts better restore alveolar clefts. Study design : Forty consecutive patients who required a unilateral alveolar cleft graft were studied. Group I (20 patients) had reconstruction with iliac cancellous particulate bone grafts and group II (20 patients) had reconstruction with iliac cancellous block bone grafts. The two groups were evaluated radiographically and clinically. Results : The group with the block bone grafts showed less postoperative problems and better incorporation of the bone graft than the group with the particulate grafts. Conclusion : Surgical reconstruction of alveolar process defects in patients with alveolar cleft using iliac cancellous block bone is a more reliable method than particulate bone grafts both for closing the oronasal fistula and for building interalveolar septal height.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.50-55
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• 1999

The exhaust emissions from diesel vehicle are known to be harmful to human health and environment. Recently, one of the most environment problems is particulate matter. In this study, through the actual exper iment and heat transfer of exhaust pipe in light duty diesel engine equipped with the ceramic filter trap of throttling type, following results are obtained. 1. In case of light duty diesel engine equipped with ceramic filter trap of throttling type, Power and torque of engine were decreased about 5%, compared with the case without trap system. It means that was not so much effect on base engine performance.2. If the length of exhaust pipe when equipping with ceramic filter trap is suitably controlled, the range of regeneration will be expand much more.3. Particulate matter reduction efficiency of ceramic filter trap system was about 70%-80%, so it was proved a good system to reduce particulate matter.In experiment, test was conducted to estimate engine emission in 2,476cc light duty diesel engine which was equipped with ceramic filter trap.