• Electrical & Electronic Materials
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• v.6 no.5
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• pp.446-453
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• 1993

초기충진압력이 서로 다른 시편에 가한 가압횟수와 열처리시간의 혼합공정이 임계전류밀도 특성에 미치는 영향을 관찰하기 위하여 power-in-tube방법으로 초전도 선재를 제조하였다. 일정 초기충진압력에서 테이프화를 위한 열처리 및 가압이 혼합공정횟수가 증가할수록 임계전류밀도가 증가하였다. 초기충진압력이 1000kg/$cm^{2}$에서 Bi-2223 고온상 체적비가 가장 높게 나타났고 결정립이 판상으로 성장되었을 뿐만 아니라 C축과 직각방향으로 잘 배양되어 있음을 관찰할 수 있었다. 특히 초기충진압력 1000kg/$cm^{2}$의 시편을 두께를 줄이기 위하여 3회 가압하고 450시간 열처리하였을때 임계전류밀도가 5800A/$cm^{2}$를 나타내었으며 이를 중심으로 500, 2500kg/$cm^{2}$이 양측단으로 가우시안분포를 보였다. 결론적으로 시편의 임계특성은 적정 초기충진압력, Bi-2223 고온상 체적비, 테이프화를 위한 가압횟수, 결정의 일방향배열, 결정립의 성장등에 강하게 의존함을 알 수 있었다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.3
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• pp.116-121
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• 2004

Treatability tests were conducted to study the feasibility of EMMC process as a recycling-water treatment system in high density seawater aquaculture farm. To study the effect of organic and ammonia nitrogen loading rate on system performance, hydraulic retention time was reduced gradually from 12hr to 10min. The conclusions are can be summarized as follows. When the system HRT was reduced from 12hr to 2hr gradually, there was little noticeable change(reduction) in ammonia nitrogen removal efficiencies. However, removal efficiencies were decreased dramatically when the system was operated under the HRT of less than 2hr. In case of organics(COD), there was no dramatic change in removal efficiencies depending on HRT reduction. COD removal efficiencies were maintained successfully higher than 9％ when the system was operated at tile HRT of 10 min. System performances depending on media packing ratio in the reactors were also evaluated. There were little differences in each reactor performances depending on media packing ratio in reactor when the reactors were operated under the HRT of longer than 1hr. However, differences in reactor performances were considerably evident when the reactors were operated under the HRT of shorter than 1hr. When comparing reactor performance among 25％, 50％,7 5％ packed reactor, it can be judged that media packing ratio more than 50％ plays no significant role in increasing reactor performance. For this reason, packing the media less than 50％ is more reasonable way in view of economic. Such a tendency shown in COD removal efficiencies well agreed with the variation of ammonia-nitrogen removal efficiencies according to the media packing ratio in reactors at each HRT. Difference in effluent ammonia-nitrogen concentration between 50％ media packing reactor and 75％ media packing reactor was negligible. When comparing with the results of 25％ packing reactor, difference was not so great.

• Journal of Chest Surgery
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• v.38 no.12 s.257
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• pp.807-814
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• 2005

Background: Cardiopulmonary bypass is an essential process to maintain circulation for saving life during the cardiac surgery, But it is a process in which systemic inflammation was evoked inevitably because of the exposure of blood to foreign surface. The injuries to distal organs during the cardiopulmonary bypass were resulted from systemic inflammation and the disturbances of micro-circulations in the organs. We designed this study to research the effects of leukocyte depletion from pump-oxygenator priming solution on the systemic inflammation, and the micro-circulation of gastric mucosa that is suggested by the gastric mucosal $CO_{2}$ partial pressure and acidity. Material and Method: The dogs were divided into three groups according to the different pump-oxygenator priming solutions; non-hemic crystalloid solution; leukocyte-depleted homologous blood; and non leukocyte-depleted homo-logous blood. Each priming solution group contained five dogs. In all three groups, 2 hours of cardiopulmonary bypass, and 4 consecutive hours of general anesthesia was maintained on the mechanical ventilation. Each dog was evaluated for the gastric mucosal pH, $CO_{2}$ partial Pressure, arterial pH, $CO_{2}$ partial pressure, the exhaled air $CO_{2}$ partial pressure and the level of IL-8 on before the cardiopulmonary bypass, 1 hour after the cardiopulmonary bypass, 2 hours after the cardiopulmonary bypass, 2 hours after the restoration of normal circulation, and 4 hours after the restoration of normal circulation after the cardiopulmonary bypass. The levels of IL-8 were measured with ELISA (enzyme linked immunosorbent assay) technique. Result: 1. There were significant differences of gastric mucosal $CO_{2}$ partial pressure between the leukocyte-depleted homologous blood group and other two groups(vs non leukocyte-depleted homologous blood group; P=0.02, vs non-hemic crystalloid solution group; P=0,01). 2. The gastric mucosal pH of leukocyte-depleted homologous blood group was significantly different from non leukocyte-depleted homologous blood group (p=0.01). 3. The levels of IL-8, which examine the systemic inflammation, showed signi- ficantly better results in leukocyte-depleted homologous blood group and non-hemic crystalloid solution group than non leukocyte-depleted homologous blood group (p=0.01, 0.01). Conclusion: Based upon these results, we concluded that the leukocyte depletion from the pump-oxygenator priming solution has a beneficial effects in reducing systemic inflammation and the preserving of gastric mucosal micro-circulation.

• Composites Research
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• v.36 no.5
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• pp.310-314
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• 2023

VaRTM(Vacuum assisted resin transfer molding) and VAP(Vacuum assisted process) processes are a type of RTM(Resin transfer molding) process, and are typical out-of-autoclave (OOA) processes that can manufacture large structures at low cost. In this paper, a resin filling test was conducted to compare the VaRTM and VAP processes, and the filling process and dimensional stability were compared. In addition, an analysis method to simulate the filling process was developed, and a dielectric sensor was used to detect the flow front of the resin, which was compared with the analysis results. From the resin filling test, the total filling time of the composite plate was measured to be 48 minutes for the VAP process and 145 minutes for the VaRTM process, and the filling time by the VAP process was reduced by about 67%. In addition, it was confirmed that the VAP process was superior to the VaRTM process in the thickness control ability and uniformity of the composite plate.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.155-156
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• 2008

물리적 분산기법으로 초음파와 균질기를 동시에 적용한 분산기법을 이용하여 에폭시 기반 층상나노실리케이트를 충진한 에폭시-나노콤포지트 제조하였다. 유리천이온도 특성으로 무충진 에폭시수지와 층상실리케이트가 충진된 나노콤포지트의 비교에서 $9.2^{\circ}C$가 상승되는 결과를 얻었다. 고온부인 $130^{\circ}C$ 환경온도에서 장시간 트리잉 절연파괴측정에서 무충진에폭시 수지에 비하여 나노콤포지트가 절연파괴시간이 13.39배 늦은 시간에 파괴되었고, 트리진전속도의 경우 나노콤포지트가 13.9배 늦은 지연속도를 나타내었다.

• Clean Technology
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• v.10 no.3
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• pp.159-168
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• 2004

Benzene adsorption experiment was carried out for activated carbon and zeolite 13X adsorbents. Single column and dual column packed with two adsorbents were used to investigate the dynamic adsorptive characteristics. Effect of feed flow rate on the breakthrough curve was not significant. Specific adsorption amount of benzene for activated carbon was larger than that for zeolite 13X. On the contrary, adsorption amount per column volume was larger for zeolite 13X column because the density of zeolite 13X was larger. In the dynamic experiment using dual adsorbents column, length of mass transfer zone was changed by the feed direction. Breakthrough time was longer and breakthrough curve was sharper when activated carbon was packed in feed inlet and zeolite 13X was packed in column outlet. Also breakthrough time and breakthrough curve slope were affected by the packing ratio of the two adsorbents.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1139-1148
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• 2000

To treat and recycle a large quantity of converter slag. the milling properties of -14/ +24 mesh-sized slag has been considered. The optimal conditions in milling process were investigated for producing powder-type slag and the required consumption was derived for the economical grinding. The characteristics of milling processes were studied in the variation of the rotational speed, milling time, filling ratio of ball, and size and amount of feed. The grinding efficiency was also examined. The optimal rotational speed in this experimental condition was observed to be the value of 79% of critical speed. The extent of grinding was increased with increasing the grinding time. but the efficiency of milling was decreased with the time. 50% ball filling was shown to have the optimal grinding effect, and less amount and small-sized feed made the milling efficiency high. As the result, using Bond's equation, power required for efficient milling was considered and the highest value was observed in the condition of high grinding time and optimal rotational speed.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.409-410
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• 2000

생물여과 (biofiltration)로 알려진 기술은 오염물을 gas stream이나 liquid stream을 사용하여 생물학적으로 처리할 수 있다. 주요 방법으로 생물세정 방법과 생물여과의 두 방법을 사용하고 있다. 오염물질 제거효율에 영향을 미치는 인자로는 오염물질의 종류와 특징, 오염물질의 유입농도, 충진물의 종류와 형상, 오염물질이 충진물에 머무름 시간 등이 있다. 일반적으로 생물 여과에 있어서 반응기의 충진물로 compost, peat, wood chips와 토양을 이용하거나 또는 활성이 없는 합성 매체를 이용하기도 한다(Leson and Winer, 1991). (중략)

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.195-202
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• 2016

In general, piston pumps are frequently used for concrete pumping. Filling coefficient signifies the ratio volume of a hydraulic cylinder to volume of concrete inside the cylinder. Therefore, it may be considered as a parameter directly affecting the flow rate and efficiency for concrete pumping. However, accurate analyses on this aspect have not yet been performed. In this paper, the data measured from horizontal pipeline pumping tests for 350m and 548m in length was analyzed to identify the relationships of rheological properties of concrete and stroke time with the filling coefficient. In addition, an equation allowing prediction of the filling coefficient from rheological properties of concrete and stroke time has been suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.261-261
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• 2009

층상실리케이트 나노입자를 포함한 에폭시수지인 나노콤포지트를 장시간 트리절연내력을 평가하기 위하여 제조하였다. 층살실리케이트를 포함하지 않은 경우보다 월등하게 긴 트리잉파괴 시간을 나타내었다. 더욱이 층상실리케이트 나노입자와 에폭시수지 계면의 효과를 연구하기위해 silane coupling agent을 나노입자에 표면처리하여 장시간 트리잉 파괴에 초점을 맞추었다. 에폭시수지와 층상실리케이트 나노입자사이 커플링 의한 계면결합은 단시간 절연파괴강도와 장시간 트리잉파괴 시간에 중요한 역할을 하고 있음을 알았다. 그 결과는 침선단에 교류 전계강도가 781.42kV/mm(교류 15kV, 침선단 곡률반경 $5{\mu}m$) 절연파괴시간을 측정한 결과 나노입자가 충진된 경우 트리개시시간이 24,726분이었고, 파괴에 이르는 시간은 29,213분이 걸렸다. 반면에 실란을 처리하지 않은 경우 파괴시간은 11,591분 이었다. 충진된 층살실리케이트 나노입자의 함량은 3wt%로 하였으며, 이와같은 파괴시간 지연 결과의 향상이 152%향상된 결과는 계면의 결합력이 크게 향상되어 나타낸 경우로 사료된다.