• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.119-128
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• 2004

DME(Dimethyl Ether) was directly produced from the synthesis gas using the slurry phase reactor. The catalyst for DME production prepared two types (A type; Cu:Zn:Al=57:33:10, B type; Cu:Zn:Al=40:45:15, molar ratio). It was evaluated for the effect of the reaction medium oil using the small size slurry phase reactor. DME production yield and the methanol selectivity decreased in the order: n-hexadecane oil> mineral oil> therminol oil. The long-term test of DME production was carried out using A and B type catalyst, and n-hexadecane oil and mineral oil, respectively. It was confirmed that the use of A type for the catalyst and n-hexadecane for the reaction medium oil was very useful for the viewpoint of the DME production form the synthesis gas.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.415-423
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• 2011

HI decomposition step certainly demand catalytic reaction for efficient production of hydrogen in SI process. Platinum catalyst can apply to HI decomposition reaction as well as hydrogenation or dehydrogenation. Generally, noble metal is used as catalyst which is loaded form for getting high dispersion and wide active area. In this study, Pt was loaded onto zirconia, ceria, alumina, and silica by impregnation method. HI decomposition reaction was carried out under the condition of $450^{\circ}C$, 1atm, and $167.76h^{-1}$ (WHSV) in a fixed bed reactor for measuring catalytic activity. And property of a catalyst was observed by BET, TEM, XRD and chemisoption analysis. On the basis of experimental results, we discussed about conversion of HI according to physical properties of the loaded Pt catalyst onto each support.

• Progress in Superconductivity and Cryogenics
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• v.17 no.4
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• pp.25-29
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• 2015

In 1987, M. K. Wu and Paul Chu discovered $Y_{1.2}Ba_{0.8}CuO_4$ (YBCO) with critical temperature ($T_c$) of 93 K. It has significantly lowered the cost of cooling of a material up to the point where superconductivity set in. Utilizing the cost reduction of attaining superconductivity and the vast amount of research to understand characteristics of high temperature oxide superconducting materials, there has been effort to use a high temperature superconductor as a coated conductor. It is important to characterize the materials precisely for stable performance before commercializing. We used polarized Raman scattering spectroscopy to study structural and stoichiometric information regarding $YBa_2Cu_3O_{7-x}$, $GdYBa_2Cu_3O_{7-x}$, and $GdBa_2Cu_3O_{7-x}$ produced by three leading groups of producing commercial grade high temperature superconductor coated conductors American Superconductor Corporation, Superpower, and SuNAM.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.89-93
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• 2009

The muscular-skeletal disorders that have become a major issue recently in Korean industrial safety area are mainly caused by manual material handling task. The objective of this study is to provide scientific data for the establishment of work safety standard for Korean workers through the experiments of lifting task under various conditions, in order to prevent the muscular-skeletal disorders in the industrial work site. This study used the psychophysical approach to determine the maximum acceptable weight(MAWL) for seven young male subjects, and used isometric and isoinertial strength variables as predictors to develop prediction models. Also, the oxygen consumption, heart rate, and RPE were measured or recorded while subjects were lifting their MAWL. Three different lifting frequencies(1, 3, 5lifts/min) with two lifting range from floor to knuckle height and knuckle to shoulder height for one hour's work shift using free style lifting technique were studied. These results may not only provide scientific data in establishing the safety standards for Korean workers' lifting tasks, but also contribute preventing the rapidly increasing muscular-skeletal disorders lately on the industrial site.

• The Korean Journal of Community Living Science
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• v.23 no.1
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• pp.5-16
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• 2012

The purpose of this study was to examine the impact of parenting stress on children's problematic behavior in multicultural families. The subjects were 143 mothers who are caring for their 3-6 year old children in multicultural families. Data was collected using a parenting stress index and a child behavior check list. The data were statistically analyzed using a t-test, a one-way ANOVA(Scheff'e test), a correlation analysis and multiple regression analysis. The study showed that there were no significant differences in parenting stress according to the socio-demographic variables. However, there were some significant differences in children's problematic behavior according to the mother's education. Correlation analysis indicated that the mother's parenting stress and children's problematic behavior in multicultural families had significant positive correlations in all sub-variables. It was also found that the mother's education, the mother's stress caused by a difficult child, the mother's stress caused by dysfuntional interactions between parents and children and educational distress, were all significant predictors of the preschool children's problematic behavior in multicultural families.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.261-264
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• 2009

We present a three-dimensional (3D) particle focusing channel using the positive dielectrophoresis (pDEP) guided by a dielectric structure between two planar electrodes. The dielectric structure between two planar electrodes induces the maximum electric field at the center of the microchannel, and particles are focused to the center of the microchannel by pDEP as they flow from the single sample injection port. Compared to the previous 3D particle focusing methods, the present device achieves the simple and effective particle focusing function without any additional fluidic ports and top electrodes. In the experimental study, approximately 90 % focusing efficiency were achieved within the focusing length of 2mm, on both x-z plane (top-view) and y-z plane (side-view) for $2{\mu}m$-diameter polystyrene (PS) bead at the applied voltage over 15 Vp-p (square wave) and at the flow rate below 0.01 ${\mu}l$/min. The present 3D particle focusing channel results in a simple particle focusing method suitable for use in integrated microbiochemical analysis system.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.4
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• pp.456-461
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• 1991

This is a case report of invasive aspergillosis of the right maxillary antrum and the left lung in a 43 year-old male patient with diabetes mellitus and liver cirrhosis. The results were as follows. 1. Invasive aspergilliosis should be considered in compromised patients who have nasal symptomatology, infraorbital swelling and pain. 2. Invasive aspergillosis is a rapidly progressive mycotic infection of the sinus which may extend to the orbit, nasal cavity and cheek. 3. Surgical intervention is particularly urgent in orbital aspergillosis in patient in whom the eyesight is still preserved. 4. Diagnosis depends upon pathological demonstration of tissue invasion by organism with the typical morphology of aspergillus species. 5. Long-term antifungal drugs should be administrated postoperatively in pathint with invasive aspergillosis.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.271-277
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• 2011

An identification method of the structural damping matrix for a steel bar by the genetic algorithm is proposed. Supposing the damping matrix were in proportion to the stiffness matrix, the proportional factors can be identified from the curve fitting of the experimental frequency response function(FRF) by the genetic algorithm. Applying the identified damping matrix to FEM of a beam model, the values of the objective function could be reduced to about 1/60 in comparison with conventional FEM model without damping. The damping matrices of some sub-structures which have large damping partly could be identified by the algorithm, and they could be used as some parts of the FEM model for a whole structure.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1027-1030
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• 2005

기존 의미커널을 적용한 주관식 채점 시스템은 여러 답안과 말뭉치에서 추출한 색인어들과의 상관관계를 벡터방식으로 표현하여 자연어 처리에 대한 문제를 해결하려 하였다. 본 논문에서는 기존 시스템의 답안 및 색인어의 표현 한계로 인한 유사도 계산오차 가능성에 대한 문제를 해결하고자 시소러스를 이용한 임의 추출 방식의 답안 확장을 적용하였다. 서술형 주관식 평가에서는 문장의 문맥보다는 사용된 어휘에 채점가중치가 높다는 점을 착안, 출제자와 수험자 모두의 답안을 동의어, 유의어 그룹으로 확장하여 채점 성능을 향상시키려 하였다. 우선 두 답안을 형태소 분석기를 이용해 색인어를 추출한 후 워드넷을 이용하여 동의어, 유의어 그룹으로 확장한다. 이들을 말뭉치 색인을 이용하여 단어들 간 상관관계를 측정하기 위한 벡터로 구성하고 의미 커널을 적용하여 정답 유사도를 계산하였다. 출제자의 채점결과와 각 모델의 채점 점수의 상관계수 계산 결과 ELSA 모델이 가장 높은 유사도를 나타내었다..

• Atmosphere
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• v.16 no.3
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• pp.225-234
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• 2006

Convective systems propagate eastward with a persistent pattern in the longitude-time space. The characteristic structure and fluctuation of convective system is helpful in determining its predictability. In this study, convective index (CI) was defined as a difference between GOES-9 window and water vapor channel brightness temperatures following Mosher (2001). Then the temporal-spatial scales and variational characteristics of the summer convective systems in the East Asia were analyzed. It is found that the average moving speed of the convective system is about 14 m/s which is much faster than the low pressure system in the summer. Their average duration is about 12 hours and the average length of the cloud streak is about 750km. These characteristics are consistent with results from other studies. Although the convective systems are forced by the synoptic system and are mostly developed in the eastern edge of the Tibetan Plateau, they have a persistent pattern, i.e., appearance of the maximum intensity of convective systems, as they approach the Korean Peninsula. The consistency of the convective systems, i.e., the eastward propagation, suggests that there exists an intrinsic predictability.