• 천문학회보
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• 제40권1호
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• pp.42.1-42.1
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• 2015

Accurately estimating black hole (BH) masses at high redshifts is imperative in the current and future era of large-area extragalactic spectroscopic surveys. We present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts, lower luminosities, and lower BH masses, comparable to the local $H{\beta}$ reverberation-mapping sample. We use data from the AGES survey and also newly acquired near-infrared spectra from the FMOS instrument on Subaru telescope for 89 broad-lined active galaxies at redshifts between 0.5 and 1.6. We focus on the MgII, CIV, and CIII broad emission lines and compare them to both $H{\alpha}$ and $H{\beta}$, using two different prescriptions to describe their emission profile width. We confirm that MgII shows a tight correlation with $H{\alpha}$, with a scatter of ~0.25 dex. The CIV and CIII estimators can be considered viable virial mass estimators, despite large scatter values. We combine our dataset with previous high redshift and high luminosity CIV and CIII measurements from the literature and we calculate a scatter of $\sim0.4$ dex and an offset to the 1:1 relation consistent with 0 for the combined sample. This updated comparison spans a total of 4 decades in BH mass, a much wider range than any previous individual study.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.639-650
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• 2008

Electricity price forecasting has become an integral part of power system operation and control. In this paper, a wavelet transform (WT) based neural network (NN) model to forecast price profile in a deregulated electricity market has been presented. The historical price data has been decomposed into wavelet domain constitutive sub series using WT and then combined with the other time domain variables to form the set of input variables for the proposed forecasting model. The behavior of the wavelet domain constitutive series has been studied based on statistical analysis. It has been observed that forecasting accuracy can be improved by the use of WT in a forecasting model. Multi-scale analysis from one to seven levels of decomposition has been performed and the empirical evidence suggests that accuracy improvement is highest at third level of decomposition. Forecasting performance of the proposed model has been compared with (i) a heuristic technique, (ii) a simulation model used by Ontario's Independent Electricity System Operator (IESO), (iii) a Multiple Linear Regression (MLR) model, (iv) NN model, (v) Auto Regressive Integrated Moving Average (ARIMA) model, (vi) Dynamic Regression (DR) model, and (vii) Transfer Function (TF) model. Forecasting results show that the performance of the proposed WT based NN model is satisfactory and it can be used by the participants to respond properly as it predicts price before closing of window for submission of initial bids.

• 복합신소재구조학회 논문집
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• 제6권1호
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• pp.51-58
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• 2015

Global buckling is a bending of pipeline and it occurs when the stability of pipeline is distributed by excessive axial force. Subesea pipeline is subjected to axial force induced by temperature and pressure from well and resulting phenomena should be controlled in appropriate manner. Global buckling of subsea pipeline is still ongoing research subject and is studied various organization. In this study, various control methods such as buoyancy module, sleeper, and snake lay for global buckling of subsea pipeline were numerically investigated with various design parameters. From the numerical simulation results, the global buckling control method using sleepers shows better results than buoyancy module and snake lay control methods in the sense of combined stress after buckling. Furthermore, the global buckling of full scale pipeline of 80km with uneven seabed profile were successfully managed when the sleeper was installed.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.379-386
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• 2015

This work presents fuel-optimal altitude maintenance of Low-Earth-Orbit (LEO) spacecrafts experiencing non-negligible air drag and J2 perturbation. A pseudospectral (direct) method is first applied to roughly estimate an optimal fuel consumption strategy, which is employed as an initial guess to precisely determine itself. Based on the physical specifications of KOrea Multi-Purpose SATellite-2 (KOMPSAT-2), a Korean artificial satellite, numerical simulations show that a satellite ascends with full thrust at the early stage of the maneuver period and then descends with null thrust. While the thrust profile is presumably bang-off, it is difficult to precisely determine the switching time by using a pseudospectral method only. This is expected, since the optimal switching epoch does not coincide with one of the collocation points prescribed by the pseudospectral method, in general. As an attempt to precisely determine the switching time and the associated optimal thrust history, a shooting (indirect) method is then employed with the initial guess being obtained through the pseudospectral method. This hybrid process allows the determination of the optimal fuel consumption for LEO spacecrafts and their thrust profiles efficiently and precisely.

• 한국임상수의학회지
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• 제21권2호
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• pp.209-213
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• 2004

A 8 kg, 3-year-old male West Highland white terrier dog with a 1.5-year history of chronic, severely pruritic, seborrheic skin disorder was referred to the Veterinary Medical Teaching Hospital of the Tokyo University of Agriculture and Technology. On physical examination, lesions were observed on entire cutaneous surface, except for face, dorsum of body, and footpads. Skin lesions were characterized by diffuse erythema, erythematous papules, severe alopecia, hyperpigmentation, and lichenification. Tape strip tests of skin lesions revealed cocci and Malassezia infections. The intradermal allergy tests revealed positive reactions to Japanese cedar pollen, but the non-seasonal clinical signs were not compatible with atopic dermatitis caused by this pollen. Results of hematological examination, serum chemistry and thyroid gland profile were normal. Examination of skin biopsy exhibited hyperplastic superficial perivascular dermatosis with severe acanthosis, excessive keratinocyte mitoses, patchy or diffuse mild spongiosis, and lymphocytic exocytosis in epidermis. Perivascular to interstitial mononuclear cells infiltration was seen in the superficial dermis. Based on the results of examination described above, epidermal dysplasia was diagnosed. Treatments with administration of antibiotics, etretinate, and prednisolone orally combined with topical ketoconazole cream and antiseborreic shampoos had no good results. Following treatment with long-term oral itraconazole at 10 mg/kg daily and chlorhexidine shampoos was successful. However, when itraconazole therapy was stopped, the condition worsened twice within 2 or 3 months. Readministration of itraconazole produced improvement within 4 weeks. This dog has now been controlled periodical itraconazole therapy.

• Current Photovoltaic Research
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• 제4권2호
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• pp.31-41
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• 2016

n-type PERT (passivated emitter, rear totally diffused) bifacial solar cells with boron and phosphorus diffusion as p+ emitter and n+ BSF (back surface field) have attracted significant research interest recently. In this work, the influences of wafer thickness, bulk lifetime, emitter, BSF on the photovoltaic characteristics of solar cells are discussed. The performance of the solar cell is determined by using one-dimensional solar cell simulation software PC1D. The simulation results show that the key role of the BSF is to decrease the surface doping concentration reducing the recombination and thus, increasing the cell efficiency. A lightly phosphorus doped BSF (LD BSF) was experimentally optimized to get low surface dopant concentration for n type bifacial solar cells. Pre-oxidation combined with a multi-plateau drive-in, using limited source diffusion was carried out before pre-deposition. It could reduce the surface dopant concentration with minimal impact on the sheet resistance.

• 한국대기환경학회지
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• 제27권3호
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• pp.326-336
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• 2011

The Light Detection and Ranging (Lidar) observation provides a specific knowledge of the temporal and vertical distribution and the optical properties of the aerosols. Unlike typical Mie scattering Lidars, which can measure backscattering and depolarization, the Raman Lidar can measure the quartz signal at the ultra violet (360 nm) and the visible (546 nm) wavelengths. In this work, we developed a method for estimating mineral quartz concentration immersed in Asian dust using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profile of the dust concentrations. The satellite observations such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) confirmed spatial distribution of Asian dust. This approach will be useful for characterizing the quartz dominated in the atmospheric aerosols and the investigations of mineral dust. It will be especially applicable for distinguishing the dust and non-dust aerosols in studies on the mixing state of Asian aerosols. Additionally, the presented method combined with satellite observations is enable qualitative and quantitative monitoring for Asian dust.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.154-159
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• 2011

The effect of the ignition delay time gap is newly studied. The operational characteristics of the linked two pyrotechnic thrusters are affected by the time gap. Although two thrusters are simultaneously ignited, the time at which the pressure starts to rise in each thruster may not be synchronized. The characteristic of the system with the time gap is compared with that of the fully synchronized system without any time gap. Depending upon the magnitude of the time gap, the pressure-time profile and the ballistic performance are different. When two pyrotechnic thrusters have a time gap, the peak pressure of one thruster(in which the pressure is built up earlier) is increased and the other is decreased. As the time gap is increased, the peak pressure is converged into the maximum pressure. This maximum pressure can be obtained when only one thruster is activated. Because the maximum pressure is bounded, it is predicted that there isn't any catastrophic failures in the considered system. When the time gap is relatively small, the impulse of the combined force acting on the moving body is almost maintained. But the ballistic performance of the system with a large time gap should be carefully estimated because the reduction of the ballistic performance should not be easily neglected.

• KSBB Journal
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• 제4권2호
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• pp.177-184
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• 1989

항생물질 발효액의 균사체 분리에 있어서 Modified regenerated cellulose 막을 이용한 Cross-flow filtration으로 높은 Flux를 얻을 수 있었다. 막분리시 가급적 높은 유속, 높은 온도, 특정 균사체농도(약 20% PMV)에서 높은 Flux를 보여주었으며 Fouling 정도는 균사체 농도가 높을수록 또한 유속이 낮을수록 심각한 것으로 나타났다. 발효액을 농축 분리할 때의 Flux profile은 1단계 Sublayer형성에 의한 급속감소, 2단계 평형, 3단계 Fouling에 의한 급속감소의 세 구간으로 나눌 수 있었으며 Diafiltration의 적용으로 3단계의 Flux 감소 현상을 현저히 완화시킬 수 있었다. 한편 Diafiltration에 의한 항생물질 회수시 초기부터Diafiltration하는 것보다는 특정 PMV까지 농축시킨 후 Diafiltration하는 경우에 작업시간과 여액의 Volume을 최소화 할 수 있었으며 본 실험에서는 98%의 회수율을 얻기 위해서 Di-afiltration을 시작하는 Optimum PMV는 20%였다.

• Geomechanics and Engineering
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• 제3권3호
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• pp.169-188
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• 2011

Response of buried flexible pipe-soil system is studied, through numerical analysis, with respect to deflection and buckling in a spatially varying soil media. In numerical modeling procedure, soil parameters are modeled as two-dimensional non-Gaussian homogeneous random field using Cholesky decomposition technique. Numerical analysis is performed using random field theory combined with finite difference numerical code FLAC 5.0 (2D). Monte Carlo simulations are performed to obtain the statistics, i.e., mean and variance of deflection and circumferential (buckling) stresses of buried flexible pipe-soil system in a spatially varying soil media. Results are compared and discussed in the light of available analytical solutions as well as conventional numerical procedures in which soil parameters are considered as uniformly constant. The statistical information obtained from Monte Carlo simulations is further utilized for the reliability analysis of buried flexible pipe-soil system with respect to deflection and buckling. The results of the reliability analysis clearly demonstrate the influence of extent of variation and spatial correlation structure of soil parameters on the performance assessment of buried flexible pipe-soil systems, which is not well captured in conventional procedures.