• 한국유체기계학회 논문집
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• 제11권2호
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• pp.13-19
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• 2008

Butterfly valves are widely used as control valves for industrial process. For the definition of optimum configuration of the valve, wide range of related studies has been actively conducted in the case of working fluids of water or air under the normal temperature. Recently, internal flow and performance characteristics of cryogenic butterfly valve for LNG carrier take a growing interest in the field of research and development. Therefore, present study is aimed to investigate the internal flow and performance characteristics of the cryogenic butterfly valve because the study result for the valve can be hardly found at present. Part 1 of this paper describes the study result of a butterfly valve model under the condition of the normal temperature. Succeeding Part 2 of this paper will describe the internal flow characteristics of a cryogenic butterfly valve for LNG carrier. The results of Part 1 show that pressure loss coefficients and flow rate coefficients obtained by the present experiment and CFD analysis agree well each other. Moreover, internal flow visualization for the valve by CFD analysis and PIV measurement have revealed complicated flow patterns of the internal flow field in detail.

• Journal of Biosystems Engineering
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• 제41권3호
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• pp.145-152
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• 2016

Purpose: This study aims to establish the effect of pinhole position errors in the planet carrier of a planetary gear set (PGS) on load sharing among the planet gears in the hydromechanical transmission (HMT) system of an agricultural tractor. Methods: A simulation model of a PGS with five planet gears was developed to analyze load sharing among the planet gears. The simulation model was verified by comparing i ts r esults w ith those of a model developed in a previous s tudy. The verified simulation model was used to analyze the load-sharing characteristics of the planet gears with respect to the pinhole position error and the input torque to the PGS. Results: Both simulation models had identical load magnitude sequences for the five planet gears. However, the load magnitudes on the corresponding planet gears differed between the models because of the different stiffnesses of the PGS components and the input torques to the PGS. The verified simulation model demonstrated that the evenness of load sharing among the planet gears increases with decreasing pinhole position error and increasing input torque. Conclusions: The geometrical tolerance of the pinhole position should be properly considered during the design of the planet carrier to improve the service life of the PGS and load sharing among the planet gears.

• 분석과학
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• 제12권3호
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• pp.224-229
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• 1999

최근 캐리어를 이용한 액체막의 연구가 대단히 활발하다. 항생물질의 모넨신을 사용하여 옥타놀의 유기용매에 용해시켜 양이온교환막을 제조하였다. 이막의 평가를 Nernst-Planck식과 Fick식으로 막전위와 물질의 투과선택도를 분석하였다. 사용한 알카리이온의 농도에 대한 높은 투과선택성을 확인하였고, 시간에 따른 이온농도값은 선형관계를 알았다. 그러나 이온의 높은농도에서 변화량은 선형이 아니였다. 이를 위한 해석은 정지층(Stagnent Layer)을 하나 더 도입하여 업 - 힐 수송에서 직선관계를 얻었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제3권2호
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• pp.149-152
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• 2001

Effect of topical application with 10, 20 and 30 ${\mu}g$/ml testosterone propionate and estradiol -17${\beta}$ on the fourth and fifth instar bivoltine NB18 silkworm larvae Bombyx mori, on the glycogen and protein contents of the Fat body and trehalose and protein contents of the haemolymph has been studied. Glycogen content of the fat body was significantly decreased in both testosterone propionate and estradiol -17${\beta}$ treatment groups except in the group treated with 30 ${\mu}g$ testosterone propionate where the increase was not significant when compared with those of carrier controls. The increase/decrease in haemolymph trehalose content did not show any significant difference in all the treated groups. Protein content of the fat body significantly increased in 10 and 20 mg testosterone propionate and estradiol -l7${\beta}$ treated groups but in 30 mg treated groups the increase was not significant when compared with those of carrier controls. There was no significant change in the haemolymph protein content in all the testosterone propionate and estradiol -17${\beta}$ treated groups except in group treated with 10 ${\mu}g$ estradiol -17${\beta}$ where it showed a significant decrease when compared with that of carrier control.

• Tribology and Lubricants
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• 제32권2호
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• pp.61-66
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• 2016

Total thickness variation (TTV), BOW, and surface roughness are essential characteristics for high quality sapphire substrates. Many researchers have attempted to increase removal rate by controlling the key process parameters like pressure and velocity owing to the high cost of consumables in sapphire chemical mechanical polishing (CMP). In case of the pressure approach, increased pressure owing to higher deviation of pressure over the wafer leads to significant degradation of the TTV. In this study, the authors focused on reducing TTV under the high-pressure conditions. When the production equipment polishes multiple wafers attached on a carrier, higher loads seem to be concentrated around the leading edge of the head; this occurs because of frictional force generated by the combination of table rotation and the height of the gimbal of the polishing head. We believe the skewed pressure distribution during polishing to be the main reason of within-wafer non-uniformity (WIWNU). The insertion of a hub ring between the polishing head and substrate carrier helped reduce the pressure deviation. Adjusting the location of the hub ring enables tuning of the pressure distribution. The results indicated that the position of the hub ring strongly affected the removal profile, which confirmed that the position of the hub ring changes the pressure distribution. Furthermore, we analyzed the deformation of the head via finite element method (FEM) to verify the pressure non-uniformity over the contact area Based on experiment and FEM results, we determined the optimal position of hub ring for achieving uniform polishing of the substrate.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.43-46
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• 2004

The large quantity of liquid wastes from nuclear industries such as nuclear power plants would become a serious storage problem in view point of the environmental safety. The liquid wastes should be concentrated to a smallest possible volume before the storage. The use of supported liquid membranes (SLMs) for this purpose is very attractive [1,2], however loss of solvent and carrier in the surrounding solutions limits the stability of SLMs and hinders their commercial application in the industries.(omitted)

• Macromolecular Research
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• 제12권1호
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• pp.71-77
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• 2004

We have synthesized various types of poly(ethylene glycol) (PEG)-ibuprofen conjugates by nucleophilic substitution of bromo-terminated PEG with ibuprofen-Cs salt. The conversion of the terminal hydroxyl groups to bromo-termini was quantitative, as was the drug conjugation process, which suggests that the present synthetic method is very useful for the preparation of PEG-based prodrugs from pharmaceuticals having carboxyl functionalities. The drug-release behavior of the prodrugs was examined in both phosphate buffer (PBS, pH 7.4) and rat plasma. From the drug-release behavior in PBS, we determined that each prodrug has high storage stability. The drug-release rate was observed to be much faster in rat plasma than in buffer solution as a result of the acceleration effect provided by enzymes present in the plasma. The drug-release rate in rat plasma depends on the degree of molecular aggregation of the prodrugs, which can be changed effectively by the nature of their spacer groups or by the use of Pluronic as the polymer carrier.

• 한국동물생명공학회지
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• 제35권2호
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• pp.207-213
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• 2020

Cryopreservation is used for blastocyst preservation of most mammalian embryos and is an important technique for breeding. We aimed to compare the efficiency of the cryopreservation method using the standard Cryotop device and the ReproCarrier device, a domestic product manufactured in Korea. The efficacy of the two devices was analyzed based on the survival rate, intracellular levels of reactive oxygen species (ROS), and apoptosis of the vitrified bovine blastocysts. The survival rates of the vitrified-warmed blastocysts were similar between the ReproCarrier group (58.4 ± 17.7%) and Cryotop group (59.9 ± 14.1%). Intracellular ROS levels and apoptotic index were determined by DCFDA staining and TUNEL assay. Changes in intracellular ROS levels, number of total nuclei, and cellular apoptosis of vitrified blastocysts after cryopreservation were not significantly different between the two groups. These results indicate that the ReproCarrier device method is as effective as the standard Cryotop method for vitrification of bovine blastocysts in vitro.

• 공업화학
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• 제26권6호
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• pp.659-665
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• 2015

지용성 토코페롤(${\alpha}$-tocopherol)의 산화 안정성을 높이기 위하여 nanostructured lipid carrier (NLC)에 봉입을 시도하였다. 먼저 구성 성분과 혼합 비율을 달리한 여러 NLC를 만들고 각각의 특성을 살펴보았다. 고체 지질로 세틸 팔미테이트 또는 글리세릴 모노스테아레이트를 사용했을 때는 안정한 상태의 NLC 입자가 만들어지지만 스테아린 산으로 만든 NLC에서는 상분리가 일어났다. NLC 입자는 수백 나노미터 크기로 만들어지는데 지질대비 용매의 비율이 높을수록 입자크기가 작게 나타났다. 고급 지방알콜인 옥틸도데칸올을 고체 지질에 첨가하면 결정화도가 감소하면서 지질 매트릭스의 배열규칙성 이 약해짐을 DSC (Differential Scanning Calorimetry) 열차트와 anisotropy 측정을 통해서 확인하였다. 고온($45^{\circ}C$) 또는 UV 빛이 조사되는 조건에서 토코페롤이 NLC에 봉입되어 있으면 용액이나 에멀젼 상태로 있는 것에 비해 산화 안정성이 크게 향상됨을 DPPH 테스트와 과산화물가 측정으로 확인하였다.

• 한국콘텐츠학회논문지
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• 제8권9호
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• pp.172-184
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• 2008

본 연구는 국내 홈네트워크 산업의 수익을 창출할 수 있는 서비스와 시장을 분석하여 활성화 전략을 제안하는 것이다. 우선 국내 홈네트워크 기술 및 제품을 분석하여 홈네트워크 산업의 가치사슬을 파악한 후, 국내 시장의 성장가능성을 측정한다. 둘째, 홈네트워크 산업을 통신사업자, 건설사업자, 컨텐츠/솔루션사업자, 전자업체로 분류한다. 셋째, 비즈니스 모델의 구성요소를 기반으로 산업별 홈네트워크 산업의 비즈니스 모델을 분석하여 홈네트워크 산업의 활성화 전략을 분석하는 것이다. 홈네트워크 비즈니스 모델은 Morris 등(2005)과 Chesbrough & Rosenbloom(2002)의 연구를 기반으로 재구성하였으며, 기업 환경 분석, 가치창출 요인 파악, 사업전략 분석, 수익과 비용 구조 파악, 포지션 분석, 경쟁 우위 요인 분석, 실행 순으로 업종별 분석을 수행하였다. 홈네트워크 산업의 활성화 전략을 파악하기 위해서 원가우위 전략, 차별화 전략, 제휴 전략을 분석하였다.