• Journal of Integrative Natural Science
• /
• v.2 no.2
• /
• pp.82-85
• /
• 2009

Distributed Bragg reflector (DBR) porous silicon (PSi) was generated by an electrochemical etching a bragg structure into a silicon wafer through electrode current in aqueous ethanolic HF solution. DBR PSi exhibiting unique reflectivity was successfully obtained by an electrochemical etching of silicon wafer using square current waveform. The multilayered photonic crystals of DBR PSi exhibited the reflection of a specific wavelength with high reflectivity in the optical reflectivity spectrum. In this work, we have developed a method to create refractive index in Si substrate through intensity of an electric current. The electrochemical process allows for precise control of the structural properties of DBR PSi such as thickness of the porous layer, porosity, and average pore diameter. The number of reflection peak of DBR PSi and its pore size increased as the intensity of electric current increased. This might be a demonstration for the fabrication of specific reflectors or filters.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.7
• /
• pp.60-69
• /
• 1996

To retrieve complex data such as images in multimedia information, we need the content-based retrieval methods based on the visual properties rather than keywords. In this paper, a contrent-based image retrieval system is desinged and implemented to retrieve images using the features of images such as colors, lines and intensity vetor features when a visual query inputs. The contents for image retrievals are the color features extracted from the color component of 16 blocks of the image, th eline features extracted form 4 lines in the image and the shape features extracted from the intensity vectors of the 16 blocks. We can either use a whole image or a sketch image for query. As the experimental results demonstrate the precision 91% the recall 33% and the average rank 3.1 the retrieval performance is found to be high. The experimental results indicate that the retrieval using the weighted features have led to substantial improvement in the percision and performance of system.

• Journal of Korea Multimedia Society
• /
• v.24 no.11
• /
• pp.1461-1471
• /
• 2021

This paper presents a light exposure correction algorithm for less pleasant images, acquired with a light metering failure. Since conventional tone mapping and gamma correction methods adopt a function mapping with the same range of input and output, the results are pleasurable for almost symmetric distributions to their intensity average. However, their corrections gave insufficient outputs for asymmetric cases at either bright or dark regions. Also, histogram modification approaches show good results on varied pattern images, but these generate unintentional noises at flat regions because of the compulsive shift of the intensity distribution. Therefore, in order to sufficient corrections for both bright and dark areas, the proposed algorithm calculates the gamma coefficients using primary parameters extracted from the global distribution. And the fusion weights are adaptively determined with complementary parameters, considering the classification information of a binary segmentation. As the result, the proposed algorithm can obtain a good output about both the symmetric and the asymmetric distribution images even with severe exposure values.

• Phonetics and Speech Sciences
• /
• v.6 no.4
• /
• pp.189-194
• /
• 2014

Objective: This study aims to investigate the speech rate, the length of a pause, habitual pitch, and voice intensity of motherese. Subjects and Methods: The research participants comprised 20 mothers (mean age 33 years). Speech data were collected and analyzed using the Real-time Pitch software (KayPENTAX(R)). Results: The average speech rate was 5.33 syllables per second without their infant present and 4.26 syllables per second with their infant present. The average pause length was 1.09 s without their infant present and 1.56 s with their infant present. The average habitual pitch was 199.79 Hz without their infant present and 227.15 Hz with their infant present. The average voice loudness was 61.09 dB without their infant present and 64.49 dB with their infant present. Conclusion: This study presented clinical information for efficiently managing the speech therapy issues of infants and children. This includes proper acoustic and phonological information to recommend to main caregivers.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.53-58
• /
• 1999

Even I the Electronic Speckle Pattern Interferometry(ESPI) method that measure the strain of object within wavelength of light is less visibility than Holographic Interferometry(HI) method, the merits of application, convenience and time-save have made the method practical in industry. However, the existing ESPI methods that are based on dual-exposure, real-time and time-average method have difficulties for accurate measurement, due to irregular intensity and shake of phase. Recently, in order to solve this problem, phase shifting method have been proposed. In this method, the path of reference light in interference is shifted to make improvement in distinction and precision. But this method includes too many noise, caused by the problem of relationship between object and phase. Therefore, a method to reduce noise muse be introduced. In this paper, least square fitting method is proposed. As results, the phase-map is influenced by precise phase shifting and current of notes and speckle pattern obtained by phase shifting method is improved on the existing method driven from time-average method.

• Korean Journal of Materials Research
• /
• v.24 no.1
• /
• pp.25-32
• /
• 2014

In this study, nano-sized cobalt oxide powder with an average particle size below 50 nm was prepared from a cobalt chloride solution by the spray pyrolysis process. The influences of reaction temperature on the properties of the generated powder were examined. The average particle size of the particles formed based on the spray pyrolysis process at a reaction temperature of $700^{\circ}C$ is roughly 20 nm. Moreover, most of these particles cannot appear with an independent type, thereby coexisting in a droplet type. When the reaction temperature increases to $800^{\circ}C$, the average particle size not only increases to roughly 40 nm but also shows a more dense structure while the ratio of particles which shows a polygonal form significantly increases. As the reaction temperature increases to $900^{\circ}C$, the distribution of the particles is from roughly 70 nm to 100 nm, while most of the particle surface is more intricately close and forms a polygonal shape. When the reaction temperature increases to $1000^{\circ}C$, the particle size distribution of the powder shows an existing form from 80 nm to at least 150 nm in an uneven form. As the reaction temperature increases, the XRD peak intensity gradually increases, yet the specific surface area gradually decreases.

• Bulletin of the Korean Space Science Society
• /
• 2010.04a
• /
• pp.39.3-39.3
• /
• 2010

Solar-terrestrial links in short-time scales(daily ~monthly) are extensively explored in recent years: such as a response of low cloud amounts to the Forbush decrease, a response of Northern Atlantic oscillation index to sudden increase in electric field intensity of solar wind and so on (e.g., Svensmark et al., 2009; Boberg & Lundstedt, 2002). In this study, we perform the superposed epoch analysis to see any possible response of the sea-level pressure over Korean peninsula to the fast solar wind stream. Data sets are daily values, and zero days are determined to be days when the solar wind velocity exceeds 800km/s. Average profile of superposed sea-level pressure shows a gradual increase during the first 2 days and a decrease afterward below the normal level with a low pressure condition maintained for a few days. This result indicates that the sea-level pressure may respond to the fast solar wind stream. In other words, the average profile of sea-level pressure mimics the average velocity profiles. The correlation coefficient between two average profiles is 0.80, with 2 day lag.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 1999.10a
• /
• pp.15-15
• /
• 1999

In chip plating, several parameters must be taken into consideration. Current density, solution concentration, pH, solution temperature, components volume, chip and media ratio, barrel geometrical shape were most likely found to have an effect to the process yields. The 3 types of barrels utilized in chip plating industry are the conventional rotating barrel. vibrational barrel (vibarrel), and the centrifugal type. Conventional rotating barrel is a close type and is commonly used. The components inside the barrel are circulated by the barrel's rotation at a horizontal axis. Process yield has known to have higher thickness deviation. The vibrational barrel is an open type which offers a wide exposure to electrolyte resulting to a stable thickness deviation. It rotates in a vertical axis coupled with multi-vibration action to facilitate mixed up and easy transportation of components, The centrifugal barrel has its plated work centrifugally compacted against the cathode ring for superior electrical contact with simultaneous rotary motion. This experiment has determined the effect of barrel vibration intensity to the plating thickness distribution. The procedures carried out in the experiment involved the overall plating process., cleaning, rinse, Nickel plating, Tin-Lead plating. Plating time was adjusted to meet the required specification. All other parameters were maintained constant. Two trials were performed to confirm the consistency of the result. The thickness data of the experiment conducted showed that the average mean value obtained from higher vibrational intensity is nearer to the standard mean. The distribution curve shown has a narrower specification limits and it has a reduced variation around the target value, Generally, intensity control in vi-barrel facilitates mixed up and easy transportation of components, However, it is desirable to maintain an optimum vibration intensity to prevent solution intrusion into the chips' internal electrode. A cathodic reaction can occur in the interface of the external and internal electrode. $2HD{\;}+{\;}e{\;}{\rightarrow}20H{\;}+{\;}H_2$ Hydrogen can penetrate into the body and create pressure which can cause cracks. At high intensity, the chip's motion becomes stronger, its contact between each other is delayed and so plating action is being controlled. However, the strong impact created by its collision can damage the external electrode's structure thereby resulting to bad plating condition. 1 lot of chip was divided into two equal partion. Each portion was loaded to the same barrel one after the other. Nickel plating and tin-lead plating was performed in the same station. Portion A maintained the normal barrel vibration intensity and portion B vibration intensity was increased two steps higher. All other parameters, current, solution condition were maintained constant. Generally, plating method find procedures were carried out in a best way to maintained the best plating condition. After plating, samples were taken out from each portion. molded and polished. Plating thickness was investigated for both. To check consistency of results. 2nd trial was done now using different lot of another characteristics.

• Journal of Ginseng Research
• /
• v.12 no.1
• /
• pp.11-29
• /
• 1988

This study was conducted to investigate the effect of light intensity and temperature on the photosynthesis and respiration of ginseng plant. Highly significant, second degree curvilinear regressions were recognized among the photosynthesis of ginseng leaves, light intensity and temperature. And an interaction between the effects of light intensity and temperature on the photosynthesis of ginseng leaves was found to be highly significant. The increasing rate of photosynthesis with the increase of light intensity was markedly decreased with increasing temperature. The light compensation point of ginseng leaves was significantly varied with temperature, and the average point was approximately 600 lux. The light saturation point of Korean ginseng was 11,000 lux at $15^{\circ}C$ and $20^{\circ}C$ and around 9,500 lux at above $25^{\circ}C$. The decreasing rate of photosynthesis with the increase of temperature significantly increased with increasing light intensity. The optimum temperature for the photosynthesis of ginseng leaves was about 15 to $22^{\circ}C$ and markedly decreased with increasing light intensity. The highest photosynthesis occurred in ginseng leaves grown with the shade of 15% transmittance. The respiration of ginseng leaves increased with the shade of 5% and/or 30% transmittance. High temperature stimulated the respiration of ginseng leaves. Percent respiration to photosynthesis of ginseng leaves grown with the shade was increased at high temperature and decreased with increasing light Intensity. It was also increased with increasing transmittance. The maximum $CO_2$ absorption of ginseng leaves grown with the shade of 5Ps and ISVS transmittance accurred at 9 o'clock a.m., whereas that of 20% transmittance occurred at 7-9 o'clock a.m. The duration of $CO_2$ absorption was distinctively long with the shade of high transmittance. The $CO_2$ compensation point in the photosynthesis of ginseng leaves was 130 ppm.

• Journal of radiological science and technology
• /
• v.20 no.2
• /
• pp.73-78
• /
• 1997

The goal of this paper is that we know the usefulness of echo-planar imaging(EPI) for discriminate between hepatocellular carcinoma(HCC) and hemangioma. We get a time signal intensity curve for liver diseases from the dynamic contrast enhancement images and compared and analyze both the contrast ratio(CR) and the contrast to noise ratio(CNR) using echo planar imaging. The obtained results are follows : 1. Hepatocellular carcinoma was shown the best contrast after about 20 seconds when Is the earlist time in the main artery, and then reduced. The center where is disease was shown the characteristic that the best contrast is appeared after about 35-45 seconds and then slowly reduced. Liver parenchyma was shown the best contrast and reduced after 60 seconds. 2. The peripheral nodular of hemangioma was shown the better contrast soon. On the other hend, the contrast of center where is disease started to increase after 60 seconds and was equal to that of liver parenchyma. Increasing of the contrast continued after. 3. Turbo SE technic was used, the average of CR for hepatocellular carcinoma was $36.7{\pm}1.2$ and the average of CNR was $2.4{\pm}3.2$, while the average of CNR for hemangioma was $54.9{\pm}1.0$ and the average of CNR was $9.7{\pm}1.3$. 4. EPI technic was used, the average of CR for hepatocellular carcinoma was $47.8{\pm}1.2$ and the average of CNR was $3.4{\pm}2.1$, while the average of CNR for hemangioma was $75.7{\pm}2.2$ and the average of CNR was $9.5{\pm}1.1$. According to above we can find that hemangioma is more bright than hepatocellular carcinoma and the difference of brightness between hepatocellular carcinoma and hemangioma is useful sequence.