• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.317-326
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• 1997

The Palmer Drought Severity Index has been ectensively used to quantitatively evaluate the drought severity at a location for both agricultural and water resources management purposes. In the present study the Palmer-type formula for drought index is drived for the whole country by analyzing the monthly rainfall and meteorological data at nine stations with a long period of records. The formula is then used to compute the monthly drought severity index at sixty-eight rainfall stations located throughout the country. For the past five significant drought periods the spatial variation of each drought is shown as a nationwide drought index map of a specified duration from which the relative severity of drought throughout the country is identifiable for a specific drought period. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Korea since 1960's. It turned out that '94-'95 drought was one of the worst both in the areal extent and drought severity. It is found that the Palmer-type formula is a very useful tool in quantitatively evaluating the severity of drought over an area as well as at a point. When rainfall and meteorological forecast become feasible on a long-term basis the method could also be utilized as a tool for drought forecasting.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.3
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• pp.297-305
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• 2014

Red ginseng (RG) contains specific ginsenosides (Rg2, Rg3) which show various pharmacological effects and absorption rate in the body better than panax ginseng. Therefore many people have been used it for health for a long time. Furthermore, many researchers have been studying its biological activities for a long times because fermentation generates lots of beneficial small molecules good for health. In this study, we fermented red ginseng with mycelium of Leatiporus sulphures var. miniatus for 7 days. As a result, we found that three ginsenosides Rg1, Re and Rb2 were decreased from 0.24, 0.25, 0.16 mg/g to 0.12, 0.1, 0.03 mg/g respectively HPLC analysis. In addition, we studied biological activities of fermented red ginseng (FRG) about skin ageing such as anti-inflammation, cell migration, anti-oxidation, collagen type 1 synthesis, and MMP-1 inhibition activities. As a result, FRG were shown higher anti-inflammatory and cell migration promoting activities than RG. FRG inhibited production of nitric oxide (NO) and mRNA expression of inducible nitric oxide synthase (iNOS) and decreased interleukin (IL)-6 induced by LPS stimulation in RAW 264.7 cells. In conclusion, this study suggest that FRG could be a potential source as a new natural anti-inflammatory agent.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.2
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• pp.147-156
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• 2017

The white cane, walking assistive device of visually impaired person, has disadvantages for acquiring the information by contacting obstacles directly and detecting low obstacle on the ground. Recently, new devices have been developing to solve these problems, but these were not widely used due to high price and appearance. Therefore, in this study, we developed two types of walking assistive shoes which were manufactured with infrared sensors, pressure sensors and vibrating motors. Two types of shoes were classified with single sensor (SS) and double sensor (DS) type according to the number of infrared sensor. To evaluate the effectiveness, we compared required time and number of collisions during walking with walking assistive shoes and white cane on obstacle area. As the results, required time was increased than white cane while number of collisions was decreased when walking with developed walking assistive shoes. In addition, required time and number of collisions was more reduced when using walking assistive device than white cane. Therefore, we suggests that developed walking assistive shoes can a great help to provide safe walking condition and reducing time to adapt new types of walking assistive shoes.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.248-253
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• 2005

We designed and fabricated a compact multi-mode interference (MMI) wavelength demultiplexer using the concept of 'Improved Quasi-State' modes. The output power and extinction ratio were improved by utilizing modal phase error which is specially occurred in low-index contrast. For a designed demultiplexer, the mode propagation analysis with effective index approximation shows significant improvement of extinction ratio to -25 dB for both $1.31{\mu}m\;and\;1.51{\mu}m$ wavelength region and the split-length was reduced about 1/5 of other MMI devices. The fabricated device shows successful characteristics for both 1.31 and $1.55{\mu}m$ wavelengths. These results demonstrate the potential of low-index materials system and the embossing process for photonic integrated circuits.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.1028-1034
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• 2005

Effects of temperature and relative humidity on contents of water-soluble vitamins (vitamins $B_1,\;B_2,\;B_3,\;B_6$, and C) of two commercial tablets ("Multivitamin Dandelion" and "Chewable vitamin C") were investigated. When stored at various temperatures (25, 35, and $45^{\circ}C$) with cap, all measured vitamins were stable and degraded very slowly during 24 weeks of storage; low relative humidity (11% RH) without cap also provided stability during storage period. At higher relative humidities (75 and 100% RH), contents of all water-soluble vitamins, except vitamins $B_2\;and\;B_3$, decreased significantly at early storage period. These results showed that stability of water-soluble vitamins is highly dependent on relative humidity rather than storage temperature.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.487-492
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• 2014

Purpose: This study relates to the development of the 3X scope, whose objective part is configured with a doublet + a meniscus lens. Methods: By the initial condition of the objective part having a configuration of a doublet + a singlet, we could optimize the optical system of scope in order to minimize the finite ray aberrations of the objective part and the whole optical system of scope, and so we could develope a new type 3X scope. Results: On the condition of the objective part having a configuration of a doublet + a singlet, when the optical system of scope was optimized in order to minimize the finite ray aberrations, we could find that the singlet became the meniscus type lens having the concave shape to the direction of the doublet, and the longer the distance between the doublet and the meniscus lens is, the more the finite ray aberrations are minimized. Conclusions: In this study, we could develope a new type 3X scope of which finite ray aberrations can be reduced to 1/14 than the existing scope by adopting the objective part of the 3X scope having a configuration of three lenses composed of a doublet + a singlet. We could confirm that this reduction of aberrations can be a means to increase the effective aperture than the existing scope and to shorten the length of the optical system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.5 s.347
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• pp.54-63
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• 2006

This work proposes a 14b 100MS/s 0.18um CMOS ADC with optimized resolution, conversion speed, die area, and power dissipation to obtain the performance required in the fourth-generation mobile communication systems. The 3-stage pipeline ADC, whose optimized architecture is analyzed and verified with behavioral model simulations, employs a wide-band low-noise SHA to achieve a 14b level ENOB at the Nyquist input frequency, 3-D fully symmetric layout techniques to minimize capacitor mismatch in two MDACs, and a back-end 6b flash ADC based on open-loop offset sampling and interpolation to obtain 6b accuracy and small chip area at 100MS/s. The prototype ADC implemented in a 0.18um CMOS process shows the measured DNL and INL of maximum 1.03LSB and 5.47LSB, respectively. The ADC demonstrates a maximum SNDR and SFDR of 59dB and 72dB, respectively, and a power consumption of 145mW at 100MS/s and 1.8V. The occupied active die area is $3.4mm^2$.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.1
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• pp.29-37
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• 1999

In general, the information processing capability of a neural network is determined by its architecture and efficient training patterns. However, there is no systematic method for designing neural network and selecting effective training patterns. Evolutionary Algorithms(EAs) are referred to as the methods of population-based optimization. Therefore, EAs are considered as very efficient methods of optimal system design because they can provide much opportunity for obtaining the global optimal solution. In this paper, we propose a new method for finding the optimal structure of neural networks based on competitive co-evolution, which has two different populations. Each population is called the primary population and the secondary population respectively. The former is composed of the architecture of neural network and the latter is composed of training patterns. These two populations co-evolve competitively each other, that is, the training patterns will evolve to become more difficult for learning of neural networks and the architecture of neural networks will evolve to learn this patterns. This method prevents the system from the limitation of the performance by random design of neural networks and inadequate selection of training patterns. In co-evolutionary method, it is difficult to monitor the progress of co-evolution because the fitness of individuals varies dynamically. So, we also introduce the measurement method. The validity and effectiveness of the proposed method are inspected by applying it to the visual servoing of robot manipulators.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.89-98
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• 2009

In the field of computer vision, image mosaicking is a common method for effectively increasing restricted the field of view of a camera by combining a set of separate images into a single seamless image. Image mosaicking based on feature points has recently been a focus of research because of simple estimation for geometric transformation regardless distortions and differences of intensity generating by motion of a camera in consecutive images. Yet, since most feature-point matching algorithms extract feature points using gray values, identifying corresponding points becomes difficult in the case of changing illumination and images with a similar intensity. Accordingly, to solve these problems, this paper proposes a method of image mosaicking based on feature points using color information of images. Essentially, the digital values acquired from a digital color camera are converted to values of a virtual camera with distinct narrow bands. Values based on the surface reflectance and invariant to the chromaticity of various illuminations are then derived from the virtual camera values and defined as color-invariant values invariant to changing illuminations. The validity of these color-invariant values is verified in a test using a Macbeth Color-Checker under simulated illuminations. The test also compares the proposed method using the color-invariant values with the conventional SIFT algorithm. The accuracy of the matching between the feature points extracted using the proposed method is increased, while image mosaicking using color information is also achieved.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.98-104
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• 1993

The paramagnetic organoruthenium(III) complexes $({\eta}^5-C_5Me_5)RuCl_2(PR_3) (PR_3 = PMe_3,\;PEt_3,\;PiPr_3,\;PCy_3,\;PMe_2Ph,\;PMePh_2,\;PPh_3,\;P(p-C_6H_4CH_3)_3$, DPPE, DPPB, Py) (2a∼2k) were synthesized by the reaction of $[({\eta}^5-C_5Me_5)RuCl_2]_2$ (1) with 1 equivalent of the corresponding phosphines $(PR_3)$. The effective magnetic moment ((${\mu}_{eff} = 1.65∼2.07 B.M.$)) derived from the magnetic susceptibility measurements of the complexes (2a∼2k) were consistent with the presence of a "single" unpaired electron in the molecule. Treatment of dichlororuthenium (III) complex ({\eta}^5-C_5Me_5)RuCl_2(PR_3)$ (2) (i) with KBr in acetone afforded the dibromoruthenium (III) complex $({\eta}^5-C_5Me_5)RuBr_2(PR_3) (PR_3 = PPh_3)$, (ii) with sodium amalgam in diethylether led to the bis(phosphine) derivatives $({eta}^5-C_5Me_5)RuCl(PR_3)_2 (PR_3 = PMe_3,\;PMePh_2)$, and (iii) with carbonmonoxide gave to the carbonyl derivatives $({\eta}^5-C_5Me_5)RuCl(PR_3)(CO) (PR_3 = PMe_3,\;PPh_3)$.