• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.307-310
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• 2016

The operational cost for maintaining the superconductivity of high-temperature superconducting (HTS) cables needs to be reduced for feasible operation. It depends on factors such as AC loss and heat transfer from the outside. Effective operation requires design optimization and suitable operational conditions. Generally, it is known that critical currents increase and AC losses decrease as the operational temperature of liquid nitrogen ($LN_2$) is lowered. However, the cryo-cooler consumes more power to lower the temperature. To determine the effective operational temperature of the HTS cable while considering the critical current and AC loss, critical currents of the HTS cable conductor were measured under various temperature conditions using sub-cooled $LN_2$ by Stirling cryo-cooler. Next, AC losses were measured under the same conditions and their variations were analyzed. We used the results to select suitable operating conditions while considering the cryo-cooler's power consumption. We then recommended the effective operating temperature for the HTS cable system installed in an actual power grid in KEPCO's 154/22.9 kV transformer substation.

• Journal of IKEEE
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• v.16 no.3
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• pp.177-181
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• 2012

This paper introduces a thermal compensation circuit with improved compensation characteristic for amplifiers to provide stable output power regardless environmental temperature. The proposed thermal compensation circuit is composed of two branchline couplers having two diodes between them. And, the thermistor whose resistance varies significantly with temperature inversely and a operational amplifiers, so called as OP-amp, control the diodes in the compensations circuit to realize more effective thermal compendation characteristic compared with conventional circuit.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.396-400
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• 2003

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verifiedthe test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design..

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.980-984
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design condidering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirm approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective method in thermal-appropriate design.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.498-503
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• 2002

This paper has studied thermal characteristics of machine tool to develope high speed spindle and optimum design considering the thermal deformation. Comparing the test data of temperature measurement and structural analysis data using FEM, we verified the test validity and predicted thermal deformation, influence of spindle generation of heat, and established cooling system to prevent the thermal deformation. 1) The temperature rise of spindle system depends on increasing number of rotation and shows sudden doubling increment of number of rotation over 7,000rpm. 2) Oil jacket cooling can be effective cooling method below 8,000rpm but, over 8,000rpm, it shows the decrement of cooling effect. 3) Comparing FEM analysis results and revolution test results, we can confirmn approximate temperature change consequently, it is possible to simulate temperature rise and thermal distribution on the inside of spindle system. 4) We can confirm that simulated approach by FEM analysis can be effective mettled in thermal-appropriate design.

• Atmosphere
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• v.34 no.3
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• pp.325-336
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• 2024

Radiosonde is an important in-situ profiling instrument that measures atmospheric temperature, moisture, and wind structure from the surface to the middle stratosphere. The operational radiosonde measurements are carried out more than twice (at 0000 UTC and 1200 UTC) daily at approximately 1,300 World Meteorological Organization (WMO) stations and play a pivotal role in daily weather forecasts. It also contributes to the monitoring of atmospheric structure by providing the key physical information like temperature and pressure, forming the backbone of atmospheric (re)analyses and numerical weather forecasts. Additionally, high-resolution radiosonde profiles are used for calibration and evaluation of satellite products. Despite these advantages, radiosonde measurements are mostly limited to operational uses due to the high initial cost of ground instrument setup required for data transmission and reception. This study outlines a cost-effective (roughly one-tenth of the operational cost) method for establishing the ground station and the necessary radiosonde measurement procedures, offering guidance for individual researchers or university-level instructors.

• The Journal of Korean Medicine
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• v.29 no.3
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• pp.11-20
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• 2008

Objectives: Warm-needling is a method combining the effects of acupuncture with the effects of moxibustion. We need to standardize the characteristics of warm-needling in order to achieve consistency in its operational mechanisms and effects, which will improve clinical ability in the field of Eastern medicine. Methods: In this study, using the LabVIEW system on the warm-needling technique, we measured and compared partial temperature changes which varied according to the density of the moxa cone and the moxa cone's core peak temperature. Results& Conclusions: Examination of the warm-needle's partial temperature in relation to the cone density of the 0.8g moxa specimen suggests that a lower density of the moxa cone corresponds to a higher peak temperature and but with a shorter duration. During the effective stimulus time, the lower the density of the moxa cone, the shorter the duration of the effective stimulus time and the higher the mean temperature. Conversely, the higher the density of the moxa cone, the longer the effective stimulus time and lower the mean temperature.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.527-544
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• 2018

This paper presents a nighttime sea fog detection algorithm incorporating unsupervised learning technique. The algorithm is based on data sets that combine brightness temperatures from the $3.7{\mu}m$ and $10.8{\mu}m$ channels of the meteorological imager (MI) onboard the Communication, Ocean and Meteorological Satellite (COMS), with sea surface temperature from the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA). Previous algorithms generally employed threshold values including the brightness temperature difference between the near infrared and infrared. The threshold values were previously determined from climatological analysis or model simulation. Although this method using predetermined thresholds is very simple and effective in detecting low cloud, it has difficulty in distinguishing fog from stratus because they share similar characteristics of particle size and altitude. In order to improve this, the unsupervised learning approach, which allows a more effective interpretation from the insufficient information, has been utilized. The unsupervised learning method employed in this paper is the expectation-maximization (EM) algorithm that is widely used in incomplete data problems. It identifies distinguishing features of the data by organizing and optimizing the data. This allows for the application of optimal threshold values for fog detection by considering the characteristics of a specific domain. The algorithm has been evaluated using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) vertical profile products, which showed promising results within a local domain with probability of detection (POD) of 0.753 and critical success index (CSI) of 0.477, respectively.

• Journal of Environmental Impact Assessment
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• v.14 no.4
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• pp.157-164
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• 2005

Existing models that predict of Daily water supply include statistical models and neural network model. The neural network model was more effective than the statistical models. Only neural network model, which predict of Daily water supply, is focused on estimation of the operational control. Neural network model takes long learning time and gets into local minimum. This study proposes Neuro Genetic hybrid model which a combination of genetic algorithm and neural network. Hybrid model makes up for neural network's shortcomings. In this study, the amount of supply, the mean temperature and the population of the area supplied with water are use for neural network's learning patterns for prediction. RMSE(Root Mean Square Error) is used for a MOE(Measure Of Effectiveness). The comparison of the two models showed that the predicting capability of Hybrid model is more effective than that of neural network model. The proposed hybrid model is able to predict of Daily water, thus it can apply real time estimation of operational control of water works and water drain pipes. Proposed models include accidental cases such as a suspension of water supply. The maximum error rate between the estimation of the model and the actual measurement was 11.81% and the average error was lower than 1.76%. The model is expected to be a real-time estimation of the operational control of water works and water/drain pipes.

• Journal of Applied Reliability
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• v.18 no.2
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• pp.95-103
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• 2018

Purpose: Environment test aim to validate the guarantee of required capability of materiel against various environment conditions which exposed during materiel life-cycle. In this paper, environment test design procedure and tailoring guideline for Korean peninsula and periphery climate are proposed. Methods: To design tailoring guideline, climate data which are regarding Korean peninsula and periphery regions provided from Korea Meteorological Administration (KMA) and National Climatic Data Center (NCDC) are used. Conclusion: For effective environment test, it is important that environment test have to design in considering environment conditions during materiel life-cycle. It is concluded that the high temperature test level can be softer than the test criteria in MIL-HDBK-310, however, the low temperature test level will be expected to be $2{\sim}6^{\circ}C$ harsher than MIL-HDBK-310.