• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.231-234
• /
• 2009

일반적으로 사용자의 작업과 관련 있는 적절한 정보 또는 서비스를 제공하는 과정에서 '상황'을 사용하는 경우 이를 상황인식 시스템으로 정의한다. 상황인식 컴퓨팅 기술이 내장된 기기나 컴퓨터는 상황을 감지하여 적절하고 유용한 서비스를 제공하는 능력을 갖게 된다. 이러한 기술은 교육, 의료, 사무실 환경 등 다양한 분야에 걸쳐 활용된다. 특히 현대화된 강의실 환경은 각종 매체의 설치로 인해 전력소모가 심해지며, 매체들과 강의 환경의 효율적인 관리가 어려워지는 문제를 발생시키므로 상황인식 컴퓨팅 기술이 적용될 필요가 있다. 본 논문에서는 상황인식 기술을 이용한 강의실 관리 시스템을 제안한다. 이 관리 시스템은 다양한 센서 (온도, 조도, $CO_2$, 인체감지) 로부터 획득되는 저수준의 데이터를 사용자가 식별할 수 있는 추상화된 고수준의 정보로 변환하여 사용자에게 알려준다. 이 시스템을 구축함으로써 관리자는 강의실 내부에 설치된 매체들과 환경요소에 대한 상황을 쉽게 인식 할 수 있고, 강의실 내부의 상황변화에 대해 능동적으로 관리 할 수 있게 된다. 또한 강의실에 대한 과거의 이력정보를 검색 할 수 있음으로써 사전관리가 가능해짐에 따라 수동적인 관리로 인한 전력소비에 비해 전력절감 효과가 있고 쾌적한 강의실 환경을 학생들에게 제공 해 줄 수 있게 된다.

• Korean Journal of Materials Research
• /
• v.10 no.5
• /
• pp.360-363
• /
• 2000

Deformation in the hysteresis loop of $Pb(Zr,Ti)O_3$ (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.1
• /
• pp.60-66
• /
• 1997

The characteristics and stability of pigments produced by Monascus anka in a jar fermenter were examined The pigments produced by the mold were fractionated into four pigments, i.e., extracellular red pigment(ERP) extracellular yellow Pigment(EYP), intracellular red pigment(IRP) and intracellular yellow pigment(IYP) by the solvent fractionation method. These pigments showed characteristic absorption spectrum indicating that they were composed of different components of pigments. Each of these four pigments separated from Monascus anka were stable under ultraviolet light, fluorescent light and in dark conditions, but their color was faded rapidly under sun light. They were also very stable against temperature below 8$0^{\circ}C$, above which temperature the stability of the Pigments was decreased rapidly. Among the eight organic acids tested, tartaric and citric acids were found to be detrimental against the Monascus anka Pigments. And Cu$^{2+}$ ion showed the most deleterious effect on the color change of the pigments.s.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.6
• /
• pp.880-884
• /
• 2005

Yellow pigment of Gardenia jasminoides was converted into new pigment by whole-cell biotransformation of thirteen different microbial species. The color value of the biotransformed pigment, which was produced by Streptococcus mutans MK-34, was higher than those of other biotransformed pigments. The biotransformed pigment produced by S. mutans MK-34 dispalyed an characteristic absorption peak at 588 nm and the absorption value increased during the incubation in a jar fermentor. The effects of light and temperature $(60^{\circ}C)$ on storage stability of the biotransformed pigment were investigated. As a result, the biotransformed pigments produced by Streptococcus mutans and Bacillus subtilis were more stable than Gardenia jasminoides yellow pigment during storage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.268-268
• /
• 2006

YBCO 초전도 박막을 제조하기 위해 일반적으로 사용되는 RABiTS공정을 통해 제조된 양축 정렬된 Ni 선재 위에 직접 YBCO를 증착시키려는 시도가 많이 이루어졌다. Ni 위에 직접 증착시킨 YBCO 박막은 c-축으로 정렬되는 온도에서 Ni이 확산되어 YBCO와 반응하여 초전도 물성을 약화시킨다. 이것을 방지하기 위하여 완층층을 먼저 증착을 하는 연구를 시행하였다. 본 연구는 Ni-5at.%W(100) 기판위에 hot-wall type MOCVD (metal organic chemical vapor deposition)를 이용하여 증착을 실시하였다. 완층층으로는 Ni, YBCO와 각각 4.70%, 3.32%의 lattice mismatch를 갖는 $Yb_2O_3$를 선택하였으며, 증착 조건으로는 온도 $800\;{\sim}\;1000^{\circ}C$, 시간 3 ~ 10min, 증착압력 10 Torr의 조건에서 증착을 행하였다. $Yb_2O_3$를 형성하기 위해 산소를 이용하였으나 $Yb_2O_3$(200) 형성을 방해하는 NiO(111)이 형성되었다. 산소를 대신해 수증기를 이용하여 NiO 상이 없는 $Yb_2O_3$(200)을 형성하였다. 증착 시간과 수증기 압력에 따른 $Yb_2O_3$의 $I_{(200)}/(I_{(111)}+I_{(200)})$의 상대 회절강도비를 XRD (X-ray diffraction)를 이용하였고, 증착된 표면 형상은 SEM(scanning electron microscopy)을 통해 관찰하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.6
• /
• pp.737-743
• /
• 2014

This paper dealt with a retrofit high power LED searchlight to replace conventional 1kW halogen searchlights. The design specification meets KDS 6230-1046-1 and KS V 8469. An optical lens with the beam angle of $6^{\circ}$ was used to meet the luminous intensity of 800,000cd at $0^{\circ}$ in horizontal line. Heat dissipation of the LED searchlight adopted a free air cooling type which does not use a fan or a heat-pipe. From the test results, power consumption of the prototype LED searchlight was 148W which was saved by 85% comparing a halogen searchlight of 1kW. Luminous intensity was 945,000cd at $0^{\circ}$ in horizontal line, satisfying KS V 8469. Luminous efficacy was improved by 4.7 times higher than that of the halogen searchlights. Beam angle, color temperature, and color rendering index(CRI) was $5.4^{\circ}$, 5,500K, and 70, respectively. Surface temperature of the LED searchlight was below $60^{\circ}C$ and surrounding temperature of the SMPS installed inside was below $50^{\circ}C$ which were satisfied with the IEC 60092-306.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.16 no.3
• /
• pp.162-173
• /
• 1996

Dry magnetic particle inspection(MPI) was performed to detect the surface defects of steel ingot cast billets. Magnetic properties of several materials were characterized by the measurement of the B-H hysteresis curve. The inspection results were evaluated in terms of the magnetizing current, temperature, and the amount of magnetic particles applied to billets. Magnetic flux leakage near the defect site of interest was measured and compared with the results of calculation by the finite element method in the case of direct magnetizing current. Direct and alternating magnetizing currents for materials were deduced by the comparison of the inspections. Results of the magnetic particle inspection by direct magnetizing current were compared with those of finite element method calculations, which were verified by measuring magnetic leakage flux above the surface and the surface defects of the material. For square rods, due to the geometrical effect, the magnetic flux density at the edges along the length of the rods was about 30% of that at the center of rod face for a sufficiently large direct magnetizing current, while it was about 70% for an alternating magnetizing current. Thus, an alternating magnetizing current generates rather uniform magnetic flux density over the rods, except for the region on the face across about 10 mm from the edge. The attraction of the magnetic particle by the magnetic leakage field was nearly independent of the surface temperature of the billets up to $150^{\circ}C$. However, the temperature should have been limited below $60^{\circ}C$ for an effective fixing of gathered magnetic particles to the billet surface using methylene chloride. We also found that the amount of applied magnetic particles tremendously affected the detection capability.

• Progress in Superconductivity
• /
• v.9 no.1
• /
• pp.62-67
• /
• 2007

The effects of the heat-treatment temperature on the carbon (C) substitution amount, full width at half maximum (FWHM) value, critical temperature ($T_c$), critical current density ($J_c$) have been investigated for 10 wt % malic acid ($C_4H_6O_5$)-doped $MgB_2/Fe$ wires. All the samples were fabricated by the in-situ powder-in-tube (PIT) method and heat-treated within a temperature range of $650^{\circ}C$ to $1000^{\circ}C$. As the heat-treatment temperature increased, it seemed that the lattice distortion was increased by a more active C substitution into the boron sites from the malic acid addition. These increased electron scattering defects seemed to enhance the $J_c-H$ properties in spite of an improvement in the crystallinity, such as a decrease of the FWHM value and an increase of the $T_c$. Compared to the un-doped wire heat-treated at $650^{\circ}C$ for 30 min, the $J_c$ was enhanced by the C doping in a high-field regime. The wire heat-treated at $900^{\circ}C$ resulted in a higher magnetic $J_c$ of approximately $10^4\;A/cm^2$ at 5 K and 8 T.

• Journal of Korea Society of Industrial Information Systems
• /
• v.25 no.1
• /
• pp.25-30
• /
• 2020

Three-phase multi-layer high temperature superconducting coaxial (TPMHTSC) cable is being actively studied due to advantages such as the reduction of the amount of superconducting wire usage and the miniaturization of the cable. The electrical characteristics of TPMHTSC cables differ from those of conventional superconducting cables, so sufficient analysis is required to apply them to the actual system. In this paper, the authors modeled 22.9 kV, 60 MVA TPMHTSC cable and analyzed the transient characteristics using a PSCAD/EMTDC-based simulation. As a result, when a fault current flows in TPMHTSC cable, most of the fault current is bypassed through the copper former layers. At this time, the total cable temperature increased by about 5 K. Through this study, we can verify the reliability of the TPMHTSC cable against the transient state, and it can be helpful for the practical application of the cable in the future.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.5
• /
• pp.57-64
• /
• 2001

The high speed in the wire-drawing process to meet the demands for the increased productivity has a great effect on the heat generated due to plastic deformation and friction between the wire and the drawing dies. During the high carbon steel wire drawing process, the temperature rise gives a great influence to the fracture of wire. In this paper, to control the temperature rise in the wire after the deformation through the drawing die, the calculation method of the wire temperature, which includes the temperature rise in the deformation zone as well as the temperature drop in the block considering the heat transfer among the wire, cooling water and surrounding air, is proposed. These calculated results of the wire temperature at the inlet and exit of the drawing die at each pass are compared with the measured wire temperatures and verified its efficiency. So, using the program to predict the wire temperature, the isothermal pass schedule program was developed. By applying this isothermal pass schedule program to the conventional process condition, a new isothermal pass schedule is redesigned through all passes. As a result, the possibility of wire fracture could be considerably reduced and the productivity of final product could be more increased than before.