• The Korean Journal of Ecology
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• v.25 no.3 s.107
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• pp.145-152
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• 2002

Saussurea chabyoungsanica was recorded in new species by Lim Hyoung Tak in 1997. In order to understand the entity of new species, we investigated the new distribution sites, vegetation structure and soil environmental factors. Additionally discovered distribution sites of S. chabyoungsanica were Manduckbong, Mt. Sukbyoung, Mt. Duckhang, and Sukgaejae, which were located on ridge of the Taebaek Mountains. Those sites are typical limestone zones of Korea and among them Sukgaejae belongs to lower great limestone area and Manduckbong, Mt. Sukbyoung and Mt. Duckhang belong to upper great limestone area. According to the result of phytosociological study, plant communities of S. chabyoungsanica were classified by 1 Community group, 4 Communities and 2 Subcommunities; Carex humilis var. nana-Saussurea chabyoungsanica Community group in wide sense Quercus mongolica Community group, Lespedeza maximowiczii-Saussurea chabyounsanica Community, Galium kinuta-Saussurea chabyoungsanica Community, Salvia chanryonica-Saussurea chabyoungsanica Community, Zabelia coreana-Saussurea chabyoungsanica Community. Environmental factor analysis of habitat showed that the distribution site of S. chabyoungsanica was ridge of North aspect and displayed pH $7{\sim}8$ typical of limestone. Soil moisture content was high, whereas organic matter content was low. Considering its high occurrence in sites of $1{\sim}10cm$ in soil depth, and of $30{\sim}45%$ in relative light intensity, major distribution sites were outcrops and boundaries between shrubland and forest. After community division by vegetation structure in habitat of S. chabyoungsanica, we investigated characters of soil environment by community. As a result of PCA analysis of soil sample by community, it was possible to divide community by characters of soil environmental factor. The cumulative value of contribution rate represented in second dimension space was 73% and the major factors for that value were soil texture, organic matter content and field capacity.

• The Korean Journal of Ecology
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• v.25 no.2
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• pp.75-82
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• 2002

Saussurea chabyoungsanica was recorded in new species by Lim Hyoung Tak in 1997. In order to understand the entity of new species, we investigated the new distribution sites, vegetation structure and soil environmental factors. Additionally discovered distribution sites of S. chabyoungsanica were Manduckbong, Mt. Sukbyoung, Mt. Duckhang, and Sukgaejae, which were located on ridge of the Taebaek mountains. Those sites are typical limestone zones of Korea and among them Sukgaejae belongs to lower great limestone area and Manduckbong, Mt. Sukbyoung and Mt. Duckhang belong to uper great limestone area. According to the result of phytosociological study, plant communities of S. chabyoungsanica were classified by 1 Community group, 4 Communities and 2 Subcommunities; Carex humilis var. nana - Saussurea chabyoungsanica Community group in wide sense Quercus mongolica Community group, Lespedeza maximowiczii- Saussurea chabyoungsanica Community, Galium kinuta - Saussurea chabyongsanica Community, Saliva chanryonica - Saussurea chabyoungsanica Community, Zabelia coreana - Saussurea chabyoungsanica Community. Environmental factor analysis of habitat showed that the distribution site of S. chabyoungsanica was ridge of North aspect and displayed pH 7∼8 typical of limestone. Soil moisture content was high, whereas organic matter content was low. Considering its high occurrence in sites of 1∼10cm in soil depth, and of 30∼45% in relative light intensity, major distribution sites were outcrops and boundaries between shrubland and forest. After community division by vegetation structure in habitat of S. chabyoungsanica, we investigated characters of soil environment by community. As a result of PCA analysis of soil sample by community, it was possible to divide community by characters of soil environmental factor. The cumulative value of contribution rate represented in second dimension space was 73% and the major factors for that value were soil texture, organic matter content and field capacity.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.123-133
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• 2010

A statistical evaluation methodology was developed to determine the compliance of candidate waste stream with clearance criteria based upon distribution of radionuclide in a waste stream at a certain confidence level. For the cases where any information on the radionuclide distribution is not available, the relation between arithmetic mean of radioactivity concentration and its acceptable maximum standard deviation was demonstrated by applying widely-known Markov Inequality and One-side Chebyshev Inequality. The relations between arithmetic mean and its acceptable maximum standard deviation were newly derived for normally or lognormally distributed radionuclide in a waste stream, using probability density function, cumulative density function, and other statistical relations. The evaluation methodology was tested for a representative case at 95% of confidence level and 100 Bq/g of clearance level of radioactivity concentration, and then the acceptable range of standard deviation at a given arithmetic mean was quantitatively shown and compared, by varying the type of radionuclide distribution. Furthermore, it was statistically demonstrated that the allowable range of clearance can be expanded, even at the same confidence level, if information on the radionuclide distribution is available.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.345-352
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• 2002

In this paper, in order to evaluate the performance of IS-95 system reverse link in white gaussian noise and rayleigh fading environment, we suggest epochal proposal to improve computer run-time and its efficiency is verified in terms of the number of samples. MC(Monte Carlo) simulation is the most popular simulation technique lately, but MC simulation requires a number of samples at low bit error rate. Therefore, MC cannot avoid the limit of computer run-time. To alleviate these problems, we apply the suggested method called central moment technique to the reverse link of the IS-95 system and can obtain discrete probability mass functions from Nth order central moments of the less number of received signal samples than those required in MC. Continuous cumulative probability distribution function can be accurately estimated by using interpolation and the improvement effect for the number of samples is proven.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.28-34
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• 2014

A planetary gear train is more compact and endures greater amounts of transmission power compared to other gear systems. Although planetary gear systems operate in small volumes, they are capable of very high efficiency due to the compact combination of their gears in the planetary gear system. They also have outstanding efficiency of only 3% for power transmission, tantamount to the power loss that occurs in each of the shift stages. Given these advantages, planetary gear systems are used in the driving systems of, which are widely used in automobile transmissions, machine tools, semiconductor equipment, and in other areas in industrial fields. Current structural equipment requires higher efficiency and greater torque levels. According to these needs, we have designed a complex planetary gear system which creates higher levels of torque. In this paper, an evaluation of strength designs for the proposed planetary gear system was conducted to ensure the stability of the gear. In addition, a durability analysis based on Miner's rule was performed using RS B 0095 device.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.10-17
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• 2014

This work investigates two important performance metrics of underlay cooperative cognitive radio (CR) networks: Interference cumulative distribution function of licensed users and outage probability of unlicensed users. These metrics are thoroughly analyzed in realistic operating conditions such as imperfect fading channel information and strict transmit power constraint, which satisfies interference power constraint and maximum transmit power constraint, over Nakagami-m fading channels. Novel closed-form expressions are derived and subsequently validated extensively through comparisons with respective results from computer simulations. The proposed expressions are rather long but straightforward to handle both analytically and numerically since they are expressed in terms of well known built-in functions. In addition, the offered results provide the following technical insights: i) Channel information imperfection degrades considerably the performance of both unlicensed network in terms of OP and licensed network in terms of interference levels; ii) underlay cooperative CR networks experience the outage saturation phenomenon; iii) the probability that the interference power constraint is satisfied is relatively low and depends significantly on the corresponding fading severity conditions as well as the channel estimation quality; iv) there exists a critical performance trade-off between unlicensed and licensed networks.

• Journal of Communications and Networks
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• v.16 no.1
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• pp.67-80
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• 2014

Spectrum sensing is vital for secondary unlicensed nodes to coexist and avoid interference with the primary licensed users in cognitive wireless networks. In this paper, we develop models for bounding interference levels from secondary network to the primary nodes within a spectrum sensing framework. Instead of classical stochastic approaches where Poisson point processes are used to model transmitters, we consider a more practical model which takes into account the medium access control regulations and where the secondary Poisson process is judiciously thinned in two phases to avoid interference with the secondary as well as the primary nodes. The resulting process will be a modified version of the Mat$\acute{e}$rn point process. For this model, we obtain bounds for the complementary cumulative distribution function of interference and present simulation results which show the developed analytical bounds are quite tight. Moreover, we use these bounds to find the operation regions of the secondary network such that the interference constraint is satisfied on receiving primary nodes. We then obtain theoretical results on the primary and secondary throughputs and find the throughput limits under the interference constraint.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1463-1471
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• 2016

The indoor localization algorithm using the Difference Means based on Fingerprint (DMFPA) to improve the performance of indoor localization in moving Wi-Fi environment is proposed in this paper. In addition to this, the performance of the proposed algorithm is also compared with the Original Fingerprint Algorithm (OFPA) and the Gaussian Distribution Fingerprint Algorithm (GDFPA) by our developed indoor localization simulator. The performance metrics are defined as the accuracy of the average localization accuracy; the average/maximum cumulative distance of the occurred errors and the average measurement time in each reference point.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.203-210
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• 2018

This paper compares the inhibition properties of aspartic and lactic acid salts with nitrite ions and their effect on critical chloride concentration. The tests were carried employing carbon steel specimens in saturated lime solution with varying pH in the range between13 to 13.6. The critical chloride concentration was estimated through multiple specimen potentiostatic tests at potentials in the usual range for passive rebar in the alkaline concrete of atmospheric structures. During tests, chloride salt was added every 48 h until all the specimens showed localized attacks. The cumulative distribution curves, i.e. the number of corroded specimens as a function of the chlorides concentration was obtained. Furthermore, IR spectra were recorded for the evaluation of the presence of the organic inhibitors on the passivity film. The results confirmed the inhibitory effect of 0.1M aspartate comparable with nitrite ions, at a similar concentration. Addition of calcium lactate did not result in an increase in the critical chloride concentration. However, the formation of a massive scale containing the substance that could reduce the corrosion propagation was observed.

• Journal of Applied Reliability
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• v.14 no.4
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• pp.225-229
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• 2014

A one-shot device is defined as a product, system, weapon, or equipment that can be used only once. After use, the device is destroyed or must undergo extensive rebuild. Determining the reliability of a one-shot device poses a unique challenge to the manufacturers and users due to the destructive nature and costs of the testing. This paper presents a reliability growth prediction for a one-shot system. It is assumed that 1) test duration is discrete(i.e. trials or rounds); 2) trials are statistically independent; 3) the number of failures for a given system configuration is distributed according to a binomial distribution; and 4) the cumulative expected number of failures through any sequence of configurations is given by AMSAA model. When the system development is represented by three configurations and the number of trials and failures during configurations are given, the AMSAA model parameters and reliability at configuration 3 are estimated by using a reliability growth analysis software. Further, if the reliability growth predictions do not meet the target reliability, the sample size of an additional test is determined for achieving the target reliability.