• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.6
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• pp.712-720
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• 2016

The purpose of this study was to inspect ballistic match of copper bullet at 4 points by analyzing vertical deviation about shot group of the 5.56 mm common bullets and copper bullets. The 5.56 mm bullet with new copper core material was developed for mitigation of environmental pollution and harmfulness to human body. The results of this study are as follows; using the regression analysis, estimated reference value of ballistic match were 51.6 mm, 64.9 mm, 87.3 mm and 99.6 mm at 25 m, 100 m, 200 m and 250 m range respectively. When analyzing the shooting test data, alternative hypothesis(The vertical deviations are less than the reference value) was adopted as the result of analyzing data using t-test. And the values of data through tool(PRODAS) and standard trajectory equation meet requirements of estimated ballistic match respectively. In conclusion, the level of ballistic match of 5.56 mm copper bullets meets the estimated reference level through regression analysis at 4 points.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.337-343
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• 1996

In this paper, we investigate the defect detection by making use of pre-made reference image data and classify the defects by using the artificial neural network. The approach is composed of three main parts. The first step consists of a proper generation of two reference image data by using a low level morphological technique. The second step proceeds by performing three times logical bit operations between two ready-made reference images and just captured image to be tested. This results in defects image only. In the third step, by extracting four features from each detected defect, followed by assigning them into the input nodes of an already trained artificial neural network we can obtain a defect class corresponding to the features. All of the image data are formed in a bit level for the reduction of data size as well as time saving. Experimental results show that proposed algorithms are found to be effective for flexible defect detection, robust classification, and high speed process by adopting a simple logic operation.

• Biomedical Science Letters
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• v.12 no.3
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• pp.197-200
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• 2006

We analyzed total protein (TP), albumin (AL), aspartic aminotransferase (AST), alanine aminotransferase (ALT), urea nitrogen (UN), creatinine (CRE) and serum protein electrophoretic fractions in sera of rural elderly patients to evaluate the health status in rural elderly patients. We observed that the frequencies of patients showed lower level of total protein, albumin, and both total protein and albumin than them of reference range were 20.3%, 22.8% and 19.0%, respectively. The rates of patients showed higher level of AST, ALT, both of AST and ALT, UN, creatinine and both of UN and creatinine than them of reference range were 33.8%, 40.0%, 30.0%, 17.7%, 15.2% and 7.9%, respectively. Comparison of protein fractions of each patient to reference range showed that 77.2% of patients showed normal in all of patterns. Few of patients showed abnormal pattern in albumin (13.6%), ${\alpha}1-globulin (0.0%),\;{\alpha}_2-g10bulin(1.1%),\;{\beta}-globulin(1.9%)\;and\;{\gamma}-globulin(6.2%)$. These data suggest that many of rural elderly patients may suffer from heart, liver and kidney diseases. The serum protein fractions are not typical criterion to evaluate the disease, but production of proteins in rural elderly patients may be affected by liver disease and kidney disease.

• Current Optics and Photonics
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• v.3 no.6
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• pp.516-521
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• 2019

The electrical leakage levels of GaN-based light-emitting diodes (LEDs) containing leakage paths are estimated using photoluminescence (PL) and photovoltaic properties under photoexcitation conditions. The PL intensity and open-circuit voltage (V_OC) decrease because of carrier leakages depending on photoexcitation conditions when compared with reference values for typical LED chips without leakage paths. Changes of photovoltage-photocurrent characteristics and PL intensity due to carrier leakage are employed to assess the leakage current levels of LEDs with leakage paths. The current corresponding to the reduced V_OC of an LED with leakage from the photovoltaic curve of a reference LED without leakage is matched with the leakage current calculated using the PL intensity reduction ratio and short-circuit current of the LED with leakage. The current needed to increase the voltage for an LED with a leakage under photoexcitation from V_OC of the LED up to V_OC of a reference LED without a leakage is identical to the additional current needed for optical turn-on of the LED with a leakage. The leakage current level estimated using the PL and photovoltaic properties under photoexcitation is consistent with the leakage level measured from the voltage-current characteristic obtained under current injection conditions.

• Journal of Families and Better Life
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• v.9 no.1 s.17
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• pp.145-160
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• 1991

The purpose of this study is to suggest some fundamental data for the welfare of consumers by investigation some characteristics of the housewives and their attitudes toward a famous brand. For the purpose of this study, the samples were distributed to houswives who lived in Seoul. The 493 data obtained were analyzed by frequency distribution, percentile, $X^2$-test, t-test, F-test, Pearson's correlation, Duncan's multiple range test and Stepwise multiple regression analysis. The major finding were follows ; The major finding were follows ; 1) In general the score for the brand preference of the housewives was somewhat high. There were significant differences between the brand preference of the housewives and the socio-demographic, reference group variables. 2) There were significant differences between the brand image of housewives and the socio-demographic, reference group variables 3) In general the score for the dissatisfaction of the housewives was somewhat low. There were significant differences between the dissatisfaction the housewives and the socio-demographic variables. 4) The brand preference of the housewives had a positive relationship with the level of their dissatisfaction. 5) The most influential variables for the brand preference of the housewives was in the rank of reference group, income, education level.

• Journal of Power Electronics
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• v.18 no.3
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• pp.863-870
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• 2018

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

• Progress in Superconductivity
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• v.3 no.2
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• pp.151-158
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• 2002

We developed a useful SQUID magnetometer for biomagnetic applications, magnetoencepha-logram(MEG) and magnetocardiogram(MCG), etc. The SQUIDs are based on Double Relaxation Oscillation SQUID(DROS). DROS consists of two SQUIDs(signal SQUID and reference SQUID) in series, and a relaxation circuit of an inductor and a resistor. Specially we used single reference junction instead of the reference SQUID. The SQUIDs are based on hysteretic $Nb/AlO_{x}$Nb junctions, fabricated by using a simple four level process. Because DROS magnetometer has large flux-to-voltage transfer coefficient, we can use simple flux-locked loop electronics fur SQUID operation. When the DROS magnetometer was operated inside a magnetically shielded room, its average magnetic field noise was about 3 (equation omitted) at 100 Hz. This noise level is low enough to measure biomagnetic fields. In this paper, we describe noise characteristics of DROS magnetometer, depending on the operation condition . .

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.453-462
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• 2016

This paper proposes a torque control method for surface mounted permanent magnetic synchronous motor (PMSM) driven by a 2-level voltage source driven inverter, which has fast torque response and small torque ripple. The proposed torque control method follows the finite control set model predictive control (FCS-MPC) strategy. A reference state is derived at each time step for the given time varying torque reference and the cost index is defined so that the tracking error for this reference state should be penalized. The choice of an optimal output voltage vector is made first from the 6 possible active voltage vectors of the 2-level voltage source inverter. Then a modulation factor for the chosen optimal voltage vector is obtained so that the torque ripple can be reduced further. It is shown that the proposed FCS-MPC control method yields fast torque tracking response and small torque ripple through simulation and experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.458-461
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• 2011

IT related services are available in the shipborne and maritime area. As their service requirements are requested diversely, the safe and reliable embedded system based device needs increase. There are two categories in embedded system : communication/control system and various user interface needed service system. In this paper, we propose the classification of embedded system in the shipborne and maritime area and provide two reference embedded system platforms and their components. One is low-level embedded reference platform of communication/control system and the other is high-level embedded reference platform of user interface oriented system.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.603-612
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• 2022

The study aims were to evaluate a machine-learning, algorithm-based, forest biomass-estimation model to estimate subnational forest biomass and to comparatively analyze REDD+ forest reference emission levels. Time-series Landsat satellite imagery and ESA Biomass Climate Change Initiative information were used to build a machine-learning-based biomass estimation model. The k-nearest neighbors algorithm (kNN), which is a non-parametric learning model, and the tree-based random forest (RF) model were applied to the machine-learning algorithm, and the estimated biomasses were compared with the forest reference emission levels (FREL) data, which was provided by the Paraguayan government. The root mean square error (RMSE), which was the optimum parameter of the kNN model, was 35.9, and the RMSE of the RF model was lower at 34.41, showing that the RF model was superior. As a result of separately using the FREL, kNN, and RF methods to set the reference emission levels, the gradient was set to approximately -33,000 tons, -253,000 tons, and -92,000 tons, respectively. These results showed that the machine learning-based estimation model was more suitable than the existing methods for setting reference emission levels.