• Journal of IKEEE
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• v.24 no.1
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• pp.319-325
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• 2020

In this paper, a discontinuous-conduction mode (DCM) DC-DC buck converter is presented for mobile device applications. The buck converter consists of compensator for stable operations, pulse-width modulation (PWM) logic, and power switches. In order to achieve small hardware form-factor, the number of off-chip components should be kept to be minimum, which can be realized with simple and efficient frequency compensation and digital soft start-up circuits. Burst-mode operation is included for preventing the efficiency from degrading under very light load condition. The DCM DC-DC buck converter is fabricated with 0.18-um BCDMOS process. Programmable output with external resistors is typically set to be 1.8V for the input voltage between 2.8 and 5.0V. With a switching frequency of 1MHz, measured maximum efficiency is 92.6% for a load current of 100mA.

• Journal of Power Electronics
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• v.11 no.6
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• pp.870-879
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• 2011

Regulated peak power tracking (RPPT) systems such as the series structure and the series-parallel structures are commonly used in satellite space power systems. However, these structures process the solar array power or the battery power to the load through two cascaded regulators during one orbit cycle, which reduces the energy transfer efficiency. Also the battery charging time is increased due to placement of converter between the battery and the solar array. In this paper a parallel structure has been proposed which can improve the energy transfer efficiency and the battery charging time for satellite space power RPPT systems. An analogue controller is used to control all of the required functions, such as load voltage regulation and solar array stabilization with maximum power point tracking (MPPT). In order to compare the system efficiency and the battery charging efficiency of the proposed structure with those of a series (conventional) structure and a simplified series-parallel structure, simulations are performed and the results are analyzed using a loss analysis model. The proposed structure charges the battery more quickly when compared to the other two structures. Also the efficiency of the proposed structure has been improved under different modes of solar array operation when compared with the other two structures. To verify the system, experiments are carried out under different modes of solar array operation, including PPT charge, battery discharge, and eclipse and trickle charge.

• Korean Journal of Environment and Ecology
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• v.20 no.1
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• pp.70-74
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• 2006

To study for proper growing conditions of Hydrangea macrophylla var. acuminata, used as ornamental trees or sources of natural sweetenings and biological active compounds, two-year-old cuttings of the plant were subjected to different conditions, light intensity, watering, and fertilizing levels. Photosynthetic rates measured on October 2 differed significantly between two light intensity regimes, but the values measured on September 3 were not significantly different. Mean photosynthetic rates on the plot watered three times a week were higher than the cuttings on the plot watered once a week. Mean photosynthetic rates on the plot fertilized 200grams/cuttings were slightly higher than those of the cuttings on the control plot. Chlorophyll contents measured on August 2 and on September 3 were significantly different between the light intensity regimes. Chlorophyll contents measured on August 2 were significantly different between the moisture regimes, but not significantly different between the fertilizing levels. Means of leaf growth(length and width) measured the highest values on the plot watered three times a week, and on the plot in full-sun lighted.

• Journal of the Semiconductor & Display Technology
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• v.12 no.2
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• pp.13-17
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• 2013

In lighting system where several large-area organic light-emitting diode (OLED) lighting panels are involved, panel aging may appear differently from each other, resulting in a falling-off in lighting quality. To achieve uniform light output across large-area OLED lighting panels, we have employed an optical feedback circuit. Light output from each OLED panel is monitored by the optical feedback circuit that consists of a photodiode, I-V converter, 10-bit analogdigital converter (ADC), and comparator. A photodiode generates current by detecting OLED light from one side of the glass substrate (i.e., edge emission). Namely, the target luminance from the emission area (bottom emission) of OLED panels is monitored by current generated from the photodiode mounted on a glass edge. To this end, we need to establish a mapping table between the ADC value and the luminance of bottom emission. The reference ADC value corresponds to the target luminance of OLED panels. If the ADC value is lower or higher than the reference one (i.e., when the luminance of OLED panel is lower or higher than its target luminance), a micro controller unit (MCU) adjusts the pulse width modulation (PWM) used for the control of the power supplied to OLED panels in such a way that the ADC value obtained from optical feedback is the same as the reference one. As such, the target luminance of each individual OLED panel is unchanged. With the optical feedback circuit included in the lighting system, we have observed only 2% difference in relative intensity of neighboring OLED panels.

• Korean Journal of Plant Resources
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• v.28 no.6
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• pp.697-703
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• 2015

Twenty apple germplasm accessions from the Korean Genebank were successfully cryopreserved using two-step freezing to back up genetic resources maintained by field collections. This study examined the morphological and genetic stability of cryopreserved dormant apple buds that were stored in liquid nitrogen, and then rewarmed and regrown. Whole plants were regenerated directly from dormant buds through budding without an intermediary callus phase. The cryopreserved buds produced high levels of shoot formation (76.2-100%), similar to those of noncryopreserved buds (91.3-100%), with no observed differences between cryopreserved and noncryopreserved materials. Three of the twenty cryopreserved apple germplasm accessions were used to assess morphological and genetic stability. No differences in morphological characteristics including shoot length, leaf shape, leaf width/length ratio, and root length were observed between controls (fresh control and noncryopreserved) and cryopreserved plantlets. The genetic stability of regenerants (before and after cryopreservation) was investigated using inter simple sequence repeat (ISSR) markers. The ISSR markers produced 253 bands using four primers, ISSR 810, SSR 835, ISSR 864, and ISSR 899. These markers showed monomorphic banding patterns and revealed no polymorphism between the mother plant and regenerants before and after cryopreservation, suggesting that cryopreservation using two-step freezing does not affect the genetic stability of apple germplasm. These results show that two-step freezing cryopreservation is a practical method for long-term storage of apple germplasms.

• Korean Journal of Plant Resources
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• v.23 no.3
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• pp.228-232
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• 2010

The present study was carried out to elucidate the effect of girdling on the quality and harvest date of the 'Shigyoku' grapes. Among girdled vines, the interval from full bloom to harvest date was 77 days; this was as much as seven days shorter in vines receiving a 20% girdling treatment. With regards to fruit characteristics, significant differences were observed in cluster length, berry number, and berry weight in vines that received girdling treatments. There were also significant differences in cluster weight; 468.2 g, 491.6 g and 504.9 g in the control group, 10% girdling group, and 20% girdling group, respectively. Thus, the use of girdling treatments is an effective approach to increasing cluster weight by 5% in the 10% girdling treatment and 8% in the 20% girdling treatment. The 10% girdling treatment showed significant difference in terms of titrable acidity; in fact, the overall titrable acidity was relatively high among all the girdling treatments. The concentration of anthocyanin increased in 20% girdling treatment, but there were no significant differences in anthocyanin concentration among girdling treatments. Berry color developed rapidly in vines that received girdling treatment.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.3
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• pp.304-312
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• 2017

This study was carried out to evaluate the effects of yam powder addition (0~40%) on the quality characteristics and oxidative stability of yackwa made with rice flour. While most rice flour (34.35%) had a particle size more than $250{\mu}m$, 75% of yam powder had a particle size less than $65{\mu}m$. Width, height, and volume of rice yackwa added with yam powder increased with increasing yam powder content. While L and b values of rice yackwa added with yam powder decreased with increasing yam powder content, a value increased. Hardness and chewiness of rice yackwa added with yam powder increased as storage period increased at $25^{\circ}C$ for 9 days, whereas they decreased with increasing yam powder content. In a discrimination test, brown color, flavor, sweetness, and bitterness increased with increasing yam powder content, whereas hardness decreased. In a preference test, taste, texture, and overall acceptance increased with increasing yam powder content. The acid and thiobarbituric acid (TBA) values of rice yackwa added with yam powder increased as storage period increased. However, acid and TBA values of the treated groups decreased with increasing yam powder content compared to the control group. Although 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activities decreased with increasing storage period, values increased with increasing yam powder content. It was found that yackwa quality, preference, and oxidative stability increased during storage with increasing yam powder content. From these results, addition of 40% yam powder would be the optimal conditions for making rice yackwa.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.21-30
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• 2005

In this paper, we propose lane detection and trackinB algerian using B-Snake as robust algorithm. One of chief virtues of Lane detection algorithm using B-Snake is that it is possible to specify a wider range of lane structure because B-Spline conform an arbitrary shape by control point set and that it doesn't use any camera parameter. Using a robust algorithm called CHVEP, we find the vanishing point, width of lane and mid-line of lane because of the perspective parallel line and then we can detect the both side of lane mark using B-snake. To demonstrate that this algorithm is robust against noise, shadow and illumination variations in road image, we tested this algorithm about various image divided by weather-fine, rainy and cloudy day. The percentage of correct lane detection is over 95$\%$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.48-51
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• 2009

One-stage low noise amplifier (LNA) using 65 nm RF CMOS technology below 20 GHz is designed to find the optimal bias voltage and optimal width of input transistor so that the maximum figure of merit (FoM) has been achieved. If the frequency is higher than 13 GHz, the amplifier needs two-stage to achieve the higher gain. If the frequency is lower than 5 GHz, one additional capacitor between gate and source should be added to control the power under the limitation. This paper summarizes one-stage LNA overall performances below 20 GHz and this approach can also be applied to other CMOS technology of LNA designs.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.169-178
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• 2014

In this study, we investigated genetic diversity of 22 microsporidian isolates infecting tropical tasar silkworm, Antheraea mylitta collected from various geographical forest locations in the state of Jharkhand, India, using polymerase chain reaction (PCR)-based marker assay: random amplified polymorphic DNA (RAPD). A type species, NIK-1s_mys was used as control for comparison. The shape of mature microsporidians was found to be oval to elongate, measuring 3.80 to $5.10{\mu}m$ in length and 2.56 to $3.30{\mu}m$ in width. Of the 20 RAPD primers screened, 16 primers generated reproducible profiles with 298 polymorphic fragments displaying high degree of polymorphism (97%). A total of 14 RAPD primers produced 45 unique putative genetic markers, which were used to differentiate the microsporidians. Calculation of genetic distance coefficients based on dice coefficient method and clustering with un-weighted pair group method using arithmetic average (UPGMA) analysis was conducted to unravel the genetic diversity of microsporidians infecting tasar silkworm. The similarity coefficients varied from 0.059 to 0.980. UPGMA analysis generated a dendrogram with four microsporidian groups, which appear to be different from each other as well as from NIK-1s_mys. Two-dimensional distribution based on Euclidean distance matrix also revealed considerable variability among different microsporidians identified from the tasar silkworms. Clustering of few microsporidian isolates was in accordance with the geographic origin. The results indicate that the RAPD profiles and specific/unique genetic markers can be used for differentiating as well as to identify different microsporidians with considerable accuracy.