• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1285-1289
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• 2012

This study has been focused on application of ELID lapping process for mirror-surface machining of sapphire wafer. Sapphire wafer is a superior material with optic properties of high performance as light transmission, thermal conductivity, hardness and so on. High effective surface machining technology is necessary to use sapphire as various usages. The interval ELID lapping process has been set up for lapping of the sapphire material. According to the ELID lapping experimental results, it shows that 12.5 kg of load for lapping is most pertinent to ELID lapping. the surface of sapphire can be eliminated by metal bonded wheel with micron abrasives and the surface roughness of 60 nmRa can be gotten using grinding wheel of 2,000 mesh in 4.5 um, depth of cut. In this study, the chemical experiments after ELID grinding also has been conducted to check chemical reaction between workpiece and grinding wheel on ELID grinding process. It shows that the chemical reaction has not happened as the results of the chemical experiments.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.11a
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• pp.17-22
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• 2005

Generally, pixel-based classification, utilize the similarity of distances between the pixel values in feature space, is applied to land use mapping using satellite remote sensing data. But this method is Improper to be applied to the very high resolution satellite data (VHRS) due to complexity of the spatial structure and the variety of pixel values. In this paper, we performed the hierarchical classification of VHRS imagery by data fusion, which integrated LiDAR height and intensity information. MLC and ISODATA methods were applied to IKONOS-2 imagery with and without LiDAR data prior to the hierarchical classification, and then results was evaluated. In conclusion, the hierarchical method with LiDAR data was the superior than others in VHRS imagery and both MLC and ISODATA classification with LiDAR data were better than without.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.37-48
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• 2004

This study is focused on the constitutive model in order to represent brittleness and dilatancy for cohesionless soils. The constitutive model was based on an anisotropic hardening rule derived from generalized isotropic hardening nile, which includes an appropriate hardening equation for the overall strain behavior at small to large strains. The yield surface is a simple cylinder type in stress space and it makes the model practically useful. Hence dilatancy behavior in cohesionless soils could be modeled reasonably. A peak stress ratio was defined in order to model brittle stress-strain relationships. An optimized design methodology was proposed on the basis of real-coded genetic algorithm in order to determine parameters for the proposed model systematically. The material parameters were then determined by that algorithm. In order to verify the proposed model, triaxial tests were performed under $K_0$ conditions far weathered soils. In comparison with the triaxial test results under $K_0$ conditions, the proposed model could calculate appropriately the actual effective stress behavior on brittle stress-strain relationships and dilatancy.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.119-126
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• 2002

A reliability analysis is performed to investigate the influence of the uncertainty from few in-situ samples and inherent heterogeneity of the ground on the probability of failure for a rock cut slope. The results are compared with those of deterministic slope stability analysis. The random variables used are unit weight of the rock, the angle of potential slope of failure, and cohesion and internal friction angle of joints. It was found that the rock slope in which the factor of safety satisfied the minimum safety factor in the deterministic analysis has high probability of failure in the reliability analysis when the weak geological strata are involved in the cut slope. The probability of failure of rock slope is most sensitive to the mean and standard deviation of cohesion in rock joint among the random soil parameters included in the reliability analysis. Sensitivities of the mean values are larger than those of standard deviations, which means that accurate estimation of the mean for the in-situ geotechnical properties is important.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.634-643
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• 2016

In this study, we compare the quality of the mango cv. Irwin cultivated in Jeju and Okinawa by evaluating the total soluble solids (TSS) and antioxidant activity (AA) from ethanol extracts of the fruit. TSS and AA were higher in fruit cultivated at the Research Institute of Climate Change and Agriculture in Jeju (RICA) and Okinawa farm, where the low tree height cultivation method is used, than in fruit cultivated on farm in Jeju. Also, the mangiferin content of the Okinawa farm was higher than those produced on the RICA and Jeju farm house. These results suggest that the lowering tree height cultivation method improves the quality of the mango cv. Irwin.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.4
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• pp.309-316
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• 1990

Age and growth of the Marbled Sole Limanda Yokohamae in Tokyo Bay were studied by otolith reading of 1,070 fishes from May 1986 to April 1988. Examination of the outer margins of the otoliths showed that the hyaline zone as annulus was formed once a year and that its formation was completed at the end of the spawning season (Feb. to Apr.). Growth of the fish was expressed by the von Bertallinffy's equaion as Lt=255.7{1-exp[-0.505(t-0.149)]} for males and Lt=376.9{1-exp[-0.303(t-0.202)]} for females, where Lt is standard length in mm and t is age in years. It was found that the growth of males and females differs, with the females showing a higher growth than the males at each estimated age. Growth in body weight was also examined. Most of the fish examined were found to be not more than three years old, although the oldest fish were four years old for males and seven years old for females.

• Journal of Environmental Policy
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• v.2 no.2
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• pp.41-63
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• 2003

CDM(Clean Development Mechanism) project is said to be a mechanism, which profits both the investing country and the host country, while additionally contributing to the reduction of greenhouse gases of the earth as a whole. However in reality, most of the proposed projects do not end up in agreement because of the problems related to differences in recognition between the investing country and the host country of the CDM project. This outlines the background for this research which proposes a new design of institutional arrangements of CDM projects in the Northeast Asian region, mainly Japan, China and Korea. In addition, we investigate the feasibility of the proposed design. The research firstly focuses on the reduction in transaction costs that the participation of Korea will have on a Japan-China CDM project. This paper further emphasizes the potential gains that would materialize if a CDM project involved the whole Northeast Asian region, and not only one country. Our research suggests that an approximate reduction of 23% in transaction costs, and about 4% reduction in the total costs of a CDM project can be expected to follow the Korean participation. In addition to decreasing costs we find that a Korean involvement in a CDM project with Japan will lead to efficiency gains illustrated by a higher increase in the IRR(Internal rate of return) in a Japan-Korea project(11.45% to 12.21%) compared to an IRR incresement of 10.57% to 11.27% for a pure Japanese CDM project. Similar results of a rise in the IRR is found for the whole investment period of 20 years. We can hence conclude that Korean participation in a Japan-China CDM project would improve the implementation possibilities of CDM project in the Northeast Asia region.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.2
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• pp.303-310
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• 2018

Bitcoin (BTC) is a cryptocurrency proposed by Satoshi Nakamoto in 2009. Bitcoin makes its transactions with no central authorities. This decentralization is accomplished with its mining, which is an operation that makes people compete to solve math puzzles to include new transactions into block, and eventually block chains (ledger) of bitcoin. Because miners need to solve a complex puzzles, they need a lot of computing resources. In return for miners' resources, bitcoin network gives newly minted bitcoins as a reward to miners when they succeed in mining. To prevent inflation, the reward is halved every 4 years. For example, in 2009 block reward was 50 BTC, but today, the block reward is 12.5 BTC. On the other hands, exchange rate for bitcoin and Korean Won (KRW) changed drastically from 924,000 KRW/BTC (January 12th, 2017) to 16,103,306 KRW/BTC (December 10th, 2017), which made mining more attractive. However, there are no rigorous researches on the profitability of bitcoin mining. In this paper, we evaluate the profitability of bitcoin mining.

• The Korean Journal of Pain
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• v.21 no.3
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• pp.173-178
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• 2008

Background: The intrathecal (IT) $GABA_A$ receptor antagonist, bicuculline (BIC), results in tactile allodynia (TA) through disinhibition in the spinal cord. Such disinhibition is considered to be an important mechanism for neuropathic pain. Agmatine, an endogenous polyamine, has a neuro-protective effect in the central nervous system. We investigated the analgesic effects and mechanisms of agmatine action on BIC-induced TA. Methods: Male Sprague-Dawley rats, weighting 250-300 g, were subjected to implantations of PE-10 into the lumbar subarachnoid space for IT drug injection. Five days after surgery, either $10{\mu}l$ of normal saline (NS) or agmatine ($30{\mu}g$ or $10{\mu}g$) in $10{\mu}l$ NS were injected 10 min prior to BIC ($10{\mu}g$) or NMDA ($5{\mu}g$). We assessed the degree of TA (graded 0: no response, 1: mild response, 2: moderate response, 3: strong response) every 5 min for 30 min. Areas under curves and degree of TA were expressed as mean ${\pm}$ SEM. Results were analyzed using one-way ANOVA followed by a Tukey test for multiple comparisons. P < 0.05 was considered significant. Results: IT BIC-induced strong TA reached its peak and plateaued between 10 to 15 min. IT NS-NMDA induced mild transient TA for up to 15 min. Preemptive IT AG attenuated IT BIC-induced TA dose dependently and preemptive IT AG10 completely abolished the IT NMDA-induced TA. Conclusions: Preemptive IT AG attenuated the IT BIC-induced TA through inhibitory actions on postsynaptic NMDA receptor activation. AG might be a viable therapeutic option in the treatment of neuropathic pain.

• Journal of Engineering Education Research
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• v.9 no.2
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• pp.82-97
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• 2006

University entrance for technical high school students in Japan is politically promoted from a viewpoint of lifelong learning. Therefore, the Japanese universities (faculty of engineering) are pressed on the necessity of making the reform for educational methods which are based on the premise of systematic study from high school to university. In Nagasaki University, the special entrance of students who were graduated from technical high school was started from 1995. Now, we are strengthening basic academic ability for them by developmental (remedial) education under a new educational-learning model called "engineering power" cultivation. We are promoting the examination of the instructional method and the development of teaching-materials, which become adequate to the student's actual condition, with technical high school teachers and the professors of our university through the observing of student's learning process and their lesson.