• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.135-140
• /
• 2000

The characteristics of mechanical behavior were estimated for Ti-6Al-4V alloy with four kinds of microstructure prepared with heat treatments. For this study, impact test, tensile test and fatigue crack growth test were performed, and then compared mechanical properties on the four microstructures. Furthermore, for quantitative evaluation, fractal dimensions of crack pass were obtained using the box counting method. The main results obtained are summarized as follows. (1) The microstructures exhibited equiaxed microstructure, bimodal-microstructure and lamellar microstructure by heat treatment. (2) The impact absorbed energy and elongation is superior in the bimodal-microstructure, and the hardness and tensile strength are superior in the lamellar microstructure. (3) The fatigue crack growth rate is similar to all microstructures in the low ${\Delta}K$ region. The fatigue crack growth rate of equiaxed microstructure is fastest, and that of lamellar microstructure is lowest in the high ${\Delta}K$ region. (4) The fractal dimension D of lamellar microstructure is higher then that of the equiaxed microstructure and bimodal microstructure.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.4
• /
• pp.609-616
• /
• 2002

The characteristics of mechanical behavior are investigated for Ti-6Al-4V alloy. Four kinds of the specimens are prepared under different heat treatments in order to produce different microstructures. In the present investigations, impact, tensile and fatigue crack growth tests are performed for each test specimen. The results obtained through the investigations are compared. Additionally fr actal dimensions of crack pass are obtained using the box counting method. The results are, 1) the microstructures shows as equiaxed, bimodal and Widmanstatten microstructures respectively, 2) the impact energy and elongation are superior fur the bimodal microstructure, and the hardness and tensile strength are superior fur the Widmanstatten microstructure, 3) the fatigue crack growth rate is similar to all microstructures in low ΔK region while that of equiaxed microstructure is the largest, and that of Widmanstatten microstructure is the lowest in high ΔK region respectively, 4) the fractal dimension D of Widmanstatten microstructure shows higher value than that of the equiaxed and bimodal microstructures under 200 magnification view of the SEM micrographs.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.2 no.1
• /
• pp.25-32
• /
• 1969

The estimated annual catch of river fishes in the lower part of the Naktong River was derived from the questionnaire, as a part of the fundamental investigation which was carried out for the development of fisheries In that region during the period of May 1967, to June 1968. The data were submitted by fishermen, and the area covered for the present investigation is shown in Fig.1. The annual catch of the region was estimated to be about 500 tons, excluding the mussel Cerbicula elatior. Prussian carp Carassius carassius was the largest in amount followed by com-mon carp Cyprinus carpio, and then goby Synechogobius hasta, Japanese eel Anguilla japonica, mullet Mugil cephalus, ect. and in that order. Major species of the fishes of this region belong to the carp family Cyprinidae, its species counting 23 from the collection during the observation period, and the total number of species was 40, these belonging to 14 families. But occasional severe drought heavily increase the salt content of the region, and at that time the major catch of fish becomes marine fishes such as Harengula zunasi, Clupanodon Punctatus, etc.

• Journal of Soil and Groundwater Environment
• /
• v.16 no.5
• /
• pp.67-73
• /
• 2011

Groundwaters were sampled from 730 wells being used for drinking purposes during 2007-2009. These samples were analysed using a gas-flow type GPC (Gas Proportional Counter) according to the USEPA method (900.0). We obtained a gross-alpha counting TDS (total dissolved solid) efficiency curve (Y = 0.0017X2 - 0.3122X + 19.165, X = TDS, Y = efficiency, $R^2$ = 0.9734) using natural uranium standard to get gross ${\alpha}$ value of the samples. The gross alpha values ranged from MDA (minimum detectable activity) to 14.88 pCi/L and 429 samples showed values higher than MDA (< 0.9 pCi/L). Correlations of the uranium values with the total alpha values and the gross-alpha values indicate that uranium values have high impacts on gross-alpha values. Groundwater samples of study areas were classified into four regions according to the rock types; plutonic (granite) rock region (427 areas), metamorphic rock region (181 aeras), sedimentary rock region (70 areas), volcanic rock region (52 areas). Groundwater of Cretaceous granite presented the highest gross-alpha value. Gross alpha in groundwaters showed no relationship with uranium in terms of the geological ages, rocks and minerals.

• Journal of the Korean Geographical Society
• /
• v.29 no.3
• /
• pp.360-368
• /
• 1994

To this day, a number of quantitative analytical methods have been employed in clarifying regional characteristics in the discipline of geography. This paper attempted, as a part of application of those quantitative analyses, to make clear the urban functions and consequently the urban characteristics statistically by adopting newly-introduced CHAID, a sort of discriminant analyis technique. The processing of data was sonducted in two phases. To begin with, the urban functions were classified after designating twenty cities - the population of each city counting 250, 000 or more - as predictor variable, and at the same time four major urban functions like administration, marketing, finance and production as response variable. And then, preeminent functions of individual region were discriminated and concurrently classified by treating the remaining traffic, education, medicare, culture and transportation functions as predictor variable, and the following five regions as response variable: Metropolitan Seoul Area. Pusan region, Taegu region, Kwangju region and Chungcheong region. According to the result of this analysis, marketing and administration are emereed as meaningful functions in Seoul and Taegu respectively. As for the finance function only Pusan and Pucheon can be discriminated. Seoul, Pusan and Seongnam reveal their dominancy in production function. To take a look at the result of the latter analysis, the Metropolitan Seoul area shows, among other functions, strong traffic and finance functions. When it comes fo Pusan region, adminstration, education and finance functions are recorded as a leading ones, and Taegu region is preferable in education, medicare and transportation functions. In case of Kwangju region adminstration, production and education functions are discriminated from any other functions. Chungcheong region shows similar aspect with only traffic function replacing the production function of Kwangju region. Based on aforementioned anlysis, it can be said that the CHAID technique, which is capable of processing large amount of categorical data and, by presenting its outcome in the form of dendrogram, facilitates the interpretation work, is an effective, meaningful means to classify and discriminate certain geographical regions and their characteristics.

• Journal of Internet of Things and Convergence
• /
• v.5 no.2
• /
• pp.67-72
• /
• 2019

As Internet voting can take place regardless of a voter's location, the participation rate of the voters would be increased and economic costs will be reduced. But the drawback of it is that all participants have to trust the election management server. If the server colludes with the specific candidate, the other candidates cannot prove rigged election. In addition, majority of researches on Internet voting are mainly focused on the voting restricted by the region and the country. Thus, it's not appropriate for the election in Internet community such as YouTube channels. As the Internet community is composed of members from all around the world, the new type of voting model is needed. In this study, we propose the smart contract based Internet voting model applicable on the blockchain network. The proposed smart contract model consists of candidate registration, voter registration, voting and counting stages. In the proposed model, anonymity of the voter is assured in the voter registration and voting stages, and all candidates can confirm the fairness of the election in the counting stage.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.527-529
• /
• 2002

Photodynamic therapy (PDT) is a medical treatment using laser and photosensitizing drug taken up to destroy cancer cells. Singlet oxygen ($^1$0$_2$) generation is strongly related to this treatment. We have built a direct detection system monitoring feeble luminescence, in the near IR region, from $^1$0$_2$, We have comparatively studied the photophysical and photochemical properties in solution of a newly developed drug ATX-S10 and Photofrin already investigated clinically. We demonstrdted that ATX-S10 was capable of efficiently yielding $^1$0$_2$, which may lead to highly efficient PDT treatment. Successive laser excitation photobleached ATX -S10 readily in a dose-dependent manner. This result shows that ATX -S10 is useful in setting up suitable medical treatment conditions to minimize side effects.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.203-206
• /
• 2002

One of the ever-increasing demands on the performances of heterodyne interferometers is to improve the measurement resolution, of which current state-of-the-art reaches the region of sub-nanometers. We propose a new scheme of phase-measuring electronics that reduces the measurement resolution without further increase in clock speed. Our scheme adopts a super-heterodyne technique that lowers the original beat frequency to a level of 1 MHz by mixing it with electrically generated reference signal. The technique enables us to measure the phase of Doppler shift with a resolution of 1.58 nanometer at a sampling rate of 1 MHz. To avoid the undesirable decrease in the maximum measurable speed caused by the lowered beat frequency, a special from of frequency up-down counting technique is combined with the super-heterodyning. This alloys performing required phase unwrapping simply by using programmable digital gates without 2$\pi$ ambiguities up to the maximum velocity of 2.35 m/s.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.26-29
• /
• 2013

In order to estimate people crowdedness in public area, the texture based method or motion based method can be used. In this paper we have proposed a mixed method. By designating the region of interest, we made the degree of crowdedness more accurate. The feature normalization also reduced the image distortion which results from difference of camera angle. The proposed system was optimized to real time embedded hardware system.

• Journal of The Korean Astronomical Society
• /
• v.24 no.1
• /
• pp.107-116
• /
• 1991

With a modern microdensitometer and POSS glass copies, we have performed an automated star counting in two colors, blue and red, over the region containing Bok globule B361. Distribution of the measured extinction values over the projected angular distance from the cloud center was approximated by a power-law, and the resulting power-law indices for the blue and red are shown to be distinctly different from each other. The difference in the power-law index indicates that the mean dust size increases towards the cloud center. Possible physical causes for such size variation are briefly discussed.