• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.255-261
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• 2015

Purpose: purchasing status and understanding trends of Functional progressive addtions lenses buyers', Correlation analysis of the Binocular Function value to determine ADD then can be apply sales and prescriptions. Methods: Years 2011 to 2014, 298 patients who were prescribed functional progressive lenses were analysed based on the prescription data and SPSS (Ver. 20.0) was treated using the statistics. Results: Results: The average age of our customers are $27.66{\pm}11.55$ years, average addition power is $+0.73{\pm}0.36D$, customers are using take a prescription of ADD $+0.75{\pm}0.28D$ was the highest 44.33% to 132 people. Near point of convergence of 276 people (92.62%) was mostly less than 10 cm, and near point of accommodation of 134 people (44.97%) was also below 10 cm, within 11~15 cm were 122 people (40.94%). Most of people were within normal range in terms of Near point of convergence and near point of accommodation, near point of accommodation tend to be longer than Near point of convergence. As you can see this result shows most of customers need extra help in their near point of accommodation instead of they are leak at it. FCC (Fused cross cylinder) check Value and ADD (addition power) tests showed that the value of a strong correlation (p=0.00), NPC and NPA were also p=0.001, the correlation of the NPC and ADD is p=0.003, In addition, NPA and ADD also showed a significant correlations (p=0.005). Near Point of Accommodation, negative relative accommodation, and positive relative accommodation are all significantly correlated (p=0.00). The short distance-related variables of the ADD which are NPC, NPA, Age, also appeared to side correlate significantly with each other. Conclusion: Binocular function values of the subjects were highly correlated with each other so precise examination is required. when Age young people are working at short distance, low ADD values was prescribed for solving discomfort. So, in the case of early presbyopia, accommodative insufficiency, or people feel fatigue when they often working at near although their accommodation function is normal, when functional progressive lenses are prescribed, expectation of this should be exactly notified.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.649-655
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• 2016

Ni nanoparticles (NPs)-graphitic carbon nanofiber (GCNF) composites were fabricated using an electrospinning method. The amounts of Ni precursor used as catalyst for the catalytic graphitization were controlled at 0, 2, 5, and 8 wt% to improve the photovoltaic performances of the nanoparticles and make them suitable for use as counter electrodes for dye-sensitized solar cells (DSSCs). As a result, Ni NPs-GCNF composites that were fabricated with 8 wt% Ni precursors showed a high circuit voltage (0.73 V), high photocurrent density ($14.26mA/cm^2$), and superb power-conversion efficiency (6.72%) when compared to those characteristics of other samples. These performance improvements can be attributed to the reduced charge transport resistance that results from the synergetic effect of the superior catalytic activity of Ni NPs and the efficient charge transfer due to the formation of GCNF with high electrical conductivity. Thus, Ni NPs-GCNF composites may be used as promising counter electrodes in DSSCs.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.280-289
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• 2022

In this paper, we present a QRS-complex detection algorithm to calculate an accurate heartbeat and clearly recognize irregular rhythm from ECG signals. The conventional Pan-Tompkins algorithm brings false QRS detection in the derivative when QRS and noise signals have similar instant variation. The proposed algorithm uses amplitude differences in 7 adjacent samples to detect QRS-complex which has the highest amplitude variation. The calculated amplitude is cubed to dominate QRS-complex and the moving average method is applied to diminish the noise signal's amplitude. Finally, a decision rule with a threshold value is applied to detect accurate QRS-complex. The calculated signals with Pan-Tompkins and proposed algorithms were compared by signal-to-noise ratio to evaluate the noise reduction degree. QRS-complex detection performance was confirmed by sensitivity and the positive predictive value(PPV). Normal ECG, muscle noise ECG, PVC, and atrial fibrillation signals were achieved which were measured from an ECG simulator. The signal-to-noise ratio difference between Pan-Tompkins and the proposed algorithm were 8.1, 8.5, 9.6, and 4.7, respectively. All ratio of the proposed algorithm is higher than the Pan-Tompkins values. It indicates that the proposed algorithm is more robust to noise than the Pan-Tompkins algorithm. The Pan-Tompkins algorithm and the proposed algorithm showed similar sensitivity and PPV at most waveforms. However, with a noisy atrial fibrillation signal, the PPV for QRS-complex has different values, 42% for the Pan-Tompkins algorithm and 100% for the proposed algorithm. It means that the proposed algorithm has superiority for QRS-complex detection in a noisy environment.

• Journal of Digital Convergence
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• v.13 no.8
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• pp.289-294
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• 2015

This paper proposes an autonomous machine learning method applicable to the BCI(Brain-Computer Interface) is based on the self-organizing Kohonen method, one of the exemplary method of unsupervised learning. In addition we propose control method of learning region and self machine learning rule using an interactive function. The learning region control and machine learning was used to control the side effects caused by interaction function that is based on the self-organizing Kohonen method. After determining the winner neuron, we decided to adjust the connection weights based on the learning rules, and learning region is gradually decreased as the number of learning is increased by the learning. So we proposed the autonomous machine learning to reach to the network equilibrium state by reducing the flow toward the input to weights of output layer neurons.

• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.199-203
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• 2016

This study relates to the development of a program for calculating the roofed pechan prism design data. First, we set the roofed pechan prism design variables and derive the relational expressions between them. With this expressions, we could develope the program that outputs the numerical data for roofed pechan prism design when the face-length and the effective incident beam diameter are given. In fact, applying this program to the prism which is not the commercial size, we were able to calculate the design data very quickly, so that we can easily acquire the 3D structure of the actual roofed pechan prism. This means that we can quickly ensure the structural data of roofed pechan prism which is required for the product development and we are able to develop the new products related to the scope at a faster speed.

• Journal of the Korea Convergence Society
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• v.8 no.12
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• pp.299-305
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• 2017

This study relates to the development of a program for calculating the design data and estimating on the Abbe-$K{\ddot{o}}nig$ prism. First, we set the Abbe-$K{\ddot{o}}nig$ prism design variables and derive the relational expressions between them. With this expressions, we could develope the program that outputs the numerical data for the Abbe-$K{\ddot{o}}nig$ prism design and three evaluation data for the Abbe-$K{\ddot{o}}nig$ prism analysis when the face-length, the effective convergent incident angle of incident beam, and the refraction index of prism are given. In fact, applying this program to the prism which is not the commercial size, we were able to calculate the design data very quickly, and we could easily understand the optical structure of the designed Abbe-$K{\ddot{o}}nig$ prism by the three evaluation data. This means that we can quickly ensure the structural data of the Abbe-$K{\ddot{o}}nig$ prism which is required for the product development.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.83-88
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• 2020

Recently, radiation shielding sheets made of eco-friendly materials have been widely used in medical institutions. The shielding sheet is processed into a solid form by thermoforming by mixing a shielding material with a polymer material. The base is resin-based and has a limit in tensile strength, and for this purpose, fibers such as non-woven fabrics are used on the surface. The shielding sheet process technology has a problem in that the tensile strength rapidly decreases when the content of the shielding material is increased to increase the shielding performance. In order to improve this, this study intends to compare and evaluate the method of laminating and coating the fibers in the sheet process. In comparison of the three types of sheets, there was no difference in shielding performance between the fiber-coated sheet and the compression sheet, but there was a large difference in tensile strength.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.104-109
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• 2018

A non-intrusive ECG and BCG measurement system is introduced. The system is built on a auxiliary backrest of a chair. The developed system is aimed to non-intrusive assessment of cardiovascular dynamic indices such as pulse arrival time(PAT) and pre-ejection period (PEP). In the system, capacitive active electrodes and capacitive grounding were used for the non-intrusive indirect-contact ECG measurement, and EMFi pressure sensor was used for the non-intrusive BCG measurement. The capacitive active electrodes and the EMFi sensor were attached on the backrest. Using the system, ECG and BCG were successfully acquired. The measured BCG showed peaks that following ECG R peaks. It was shown that the time interval between Q wave in ECG and first peak in BCG correlates Pre-ejection period measured by impedance-cardiogram. The results showed that the introduced system can be used for the non-intrusive various cardiovascular information including ECG, PAT, PEP.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.186-192
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• 2019

In general, many marine organisms are attached to the bottom of a ship in operation or a ship in construction. Due to this phenomenon, the roughness of the ship surface increases, resulting in loss of ship speed, resulting in economic losses and environmental pollution. This study acquires / utilizes camera images attached to ship's bottom and underwater drones to check the condition of bottom. The acquired image will determine the roughness according to marine life by the administrator's visual confirmation. Therefore, by applying a filter algorithm to correct the image to the original image can help in the correct determination of whether or not attached to marine life. Various correction filters are required for the underwater image correction algorithm, and the lighting suitable for the dark underwater environment has a great influence on the judgment. The results of the research test according to the calibration algorithm and the roughness of each algorithm are considered to be applicable to many fields.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.249-255
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• 2016

Since the elderly voices include a lot of noise caused by physiological changes in respiration, phonation, and resonance, the performance of the convergence health-care equipments such as speech recognition, synthesis, analysis program done by elderly voice is deteriorated. Therefore it is necessary to develop researches to operate health-care instruments with elderly voices. In this study, a voice activity detection using a symmetric higher-order differential energy function (SHODEO) was developed and was compared with auto-correlation function(ACF) and the average magnitude difference function(AMDF). It was confirmed to have a better performance than other methods in the voice interval detection. The voice activity detection will be applied to a voice interface for the elderly to improve the accessibility of the smart devices.