• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.814-821
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• 2015

The STEP Cube Lab. classified as a pico-class satellite has been successfully developed as a flight model(FM) to be launched in 2015. Its mission objective is to perform the on-orbit verification of fundamental space core-technologies. In this study, a thermal design concept based on the passive method to achieve the mission objective is introduced. The effectiveness of the thermal design and performance of the satellite has been verified through the acceptance level thermal vacuum test. In addition, to improve the reliability of thermal mathematical model, correlation was performed using the results of thermal balance test. This paper describes a series of process for the thermal vacuum test on the STEP Cube Lab. FM.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.631-640
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• 2020

Currently, aircraft simulator has drawn a great attention because it has significant advantages of economic, temporal, and spatial costs compared with pilot training with real aircraft. Among the components of the aircraft simulator, flight dynamic model plays a key role in simulating the flight of an actual aircraft. Hence, it is important to verify the fidelity of flight dynamic model with an automated tool. In this paper, we develop a software to automatically verify the fidelity of the flight mechanics model for the efficient development of the aircraft simulator. After designing the software structure and GUI based on the requirements derived from the fidelity verification process, the software is implemented with C # language in Window-based environment. Experimental results on CTSW models show that the developed software is effective in terms of function, performance and user convenience.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.193-201
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• 2003

In this paper, a classifier of urine analysis system was designed using preprocessing and fuzzy algorithm. Preprocessing were processed by normalizing data of strip using calibration curve composed of achromatic colors value and by calculating three stimulus. FUZZY classifier capable of analyzing a qualitative concentration of test items was composed of fuzzifier by gaussian shaped membership function, inference of MIN method, and defuzzifier of centroid method through verification by measuring standard solution and by classifying concentration classes. After tuning membership function according to relating standard solution with urinalysis sample, the possibility to adapt classifier designed for urine analysis system near a bed was verified as classifying measured urinalysis samples and observing classified result. Of all test items, experimental results showed a satisfactory agreement with test results of reference system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.93-100
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• 2008

The use of fiber reinforced polymer (FRP) composites is significantly growing in construction and infrastructure applications where durability under harsh environmental conditions is of great concern. In order to examine the applicability of FRP rebar as a reinforcement in flexural member, flexural tests were conducted. 12 beams with different FRP materials such as CFRP, GFRP and Hybrid FRP and reinforcement ratio were tested and analyzed in terms of failure mode, moment-deflection, flexural capacity, ductility index and sectional strain distribution. The test results were also compared with the theoretical model represented in ACI 440.1R06. Test results indicate that the flexural capacity of the beams reinforced by FRP bars can be accurately predicted using the ultimate design theory. They also show that the current ACI model for computing the deflection overestimates the actual deflection of GFRP series and underestimates the deflection of CFRP series.

• KSBB Journal
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• v.18 no.3
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• pp.239-242
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• 2003

To develop a nicotine-degrading material (NDM), the natural herbal extract was studied. For the in vitro verification, the herbal extract was mixed into the dilute nicotine solution and the ability of NDM to degrade nicotine into cotinine was measured spectrophotometically. In the in vivo study, the rats in experimental and control groups were orally fed with the herbal extract and water, respectively, for 2 weeks. And then, 3 ㎎/㎏ nicotine was administered to both groups by intraperitoneal injection. In results, the ability of NDM to degrade nicotine into cotinine was shown 2.5 fold higher after 90 min reaction in comparison with the control group. In addition, a decrease of 33% in nicotine concentration and a increase of 57% in cotinine concentration were shown in rat blood. Therefore, NDM was shown to be effective in the conversion of nicotine into cotinine.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1159-1160
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• 2006

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, this has raised potential problems of network protection on electrical power system. One of the numerous problems is an Island phenomenon. There has been an argument that because the probability of islanding is extremely low it may be a non-issue in practice. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an island can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficient to cause a trip, plus the time required to execute the trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. And, third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an island. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. So the verification of anti-islanding performance is strongly needed. In this paper, the authors propose the improved RPV method through considering power quality and anti-islanding capacity of grid-connected three-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation and experimental results are verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.431-440
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• 2012

In this paper, new beam-forming array antenna is proposed. The proposed beam-forming array antenna has control ability for beam-direction/width by employing low loss reconfigurable power divide and three-dimensional array structure. The reconfigurable power divider is key idea in the proposed antenna, because it has reconfigurable RF power distribution ability to each antenna. And, for research and verification of the proposed antenna, 3-dimensional beam-forming array antenna is implemented, and the experimental results show that the proposed antenna has various radiation modes from 1:1 to 1:N by adjusting RF power distribution.

• Journal of the Korean Magnetics Society
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• v.24 no.4
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• pp.107-113
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• 2014

In this paper, a optimum degaussing technique, which can minimize an underwater magnetic field anomaly generated by the ferromagnetic hull, was verified through the mock-up test of a ship. To predict degaussing field signals due to the degaussing coils installed in a ship, individual coil effects were measured. Exploiting the linearity of coil effects and analytical sensitivity formula, optimum degaussing current values fed to individual coils were decided. To identify degaussing performance of the proposed method, the obtained degaussing currents were applied to the coils. Then the field anomaly signals were measured and analyzed before and after degaussing. Experimental results show the magnitude of the field signal after degaussing is reduced up to 95% of that before degaussing.

• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.174-183
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• 2014

When a active sonar signal is transmitted and returned back from a target, it has been distorted by various properties of acoustic channel such as multipath arrivals. And signals have been appeared to be different form by target position and attitude. Therefore, we simulated the target echo signal using 3 dimensional target model include reflects target features. In this paper, we develop components form of a simulated target model is made up equally spaced highlight points, and each part of the target consists of shape function. We can simulate a target echo signal and Target strength (TS) according to wave incident angle. To verify, we made small scale target in kit form and we had got underwater target signal for comparing simulation result in water tank.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.447-453
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• 2020

In this paper, we propose a system to extract effective speaker representations from a speech signal using a deep learning method. Based on the fact that speech signal contains identity unrelated information such as text content, emotion, background noise, and so on, we perform a training such that the extracted features only represent speaker-related information but do not represent speaker-unrelated information. Specifically, we propose an auto-encoder based disentanglement method that outputs both speaker-related and speaker-unrelated embeddings using effective loss functions. To further improve the reconstruction performance in the decoding process, we also introduce a discriminator popularly used in Generative Adversarial Network (GAN) structure. Since improving the decoding capability is helpful for preserving speaker information and disentanglement, it results in the improvement of speaker verification performance. Experimental results demonstrate the effectiveness of our proposed method by improving Equal Error Rate (EER) on benchmark dataset, Voxceleb1.