• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1368-1375
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• 1993

This paper deals with the decentralized robust adaptive controller design for large-scale interconnected systems. We consider an arbitrary interconnection of subsystems with unkown parameters and bounded disturbances. When the disturbance and uncertain interconnections are present, the stability of the controlled large scale system is ensured if there exists a positive definite M-matrix which is related to the bound of the interconnections. The possible bound of the interconnections is assumed to be known Pth order polynomials for the decentralized adaptive controller. A modified adaptive law is proposed guaranteeing the existence of a region of attraction from which all signals converge to a residual set Do, which contains the equilibrium.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1768-1770
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• 2016

In this paper, we propose a construction method of fractional repetition codes, a class of distributed storage codes, using relative difference families. The proposed codes can support multiple replication degrees for data symbols. It is shown via simulation that the proposed codes store more data than the random fractional repetition codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4C
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• pp.336-341
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• 2008

In this paper, beamforming algorithm is proposed which can obtain diversity gain in beamforming system that deploy antenna elements with half-wavelength. The proposed algorithm provides beam-pattern using eigen-vectors that span received signal subspace. The criterion to decide optimal rank of eigen-space used for beamforming is also proposed. A beamforming system applied the proposed algorithm shows better performance with diversity gain as getting larger angle spread. This paper provides a description of proposed algorithm with analysis of the performance using various computer simulations.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.53-59
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• 2001

There is a lot of method to manage the insanitary landfill but vertical cutoff walls have been widespreadly used and were installed into the subsurface to act as a barrier to horizontal groundwater flow, The stabilized material such as specialized cement or mixed soil with additives has been generally applied for the materials of the deep soil mixing barrier in korea. The amount of the stabilized material is dependent on the field conditions, because the mixing ratio of the material and the field soil should achieve a requirement in the coefficient of permeability, lower than 1.0$\times$$10^{7}$cm/sec. This study determined the quantity and optimized function ratio of the stabilized material in the formation process of the mixed barrier that was added with stabilized material on the field soil classified into SW-SC under USCS (Unified Soil Classification System). After that the fly ash and lime were selected as an additives an that could improve the function of the stabilized material and then the method to improve the functional progress in the usage of putting into the stabilized material as an appropriate ratio was studied and reviewed. The author used the flexible-wall permeameter for measuring the permeability and unconfined compressive strength tester for compressive strength, and in the view of environmental engineering the absorption test of heavy metals and leaching test regulated by Korean Waste Management Act were performed. As the results, the suitable mixing ratio of the stabilized material in the deep soil mixing barrier was determined as 13 percent. To make workability easy, the ratio of stabilized material and water was proven to be 1 : 1.5. With the results, the range of the portion of the additives(fly ash : lime= 70 : 30) was proven to be 20-40% for improving the function of the stabilized material, lowering of permeability. In heavy metal absorption assessment of the mixing barrier system with the additives, the result of heavy metal absorption was proved to be almost same with the case of the original stabilized material; high removal efficiency of heavy metals. In addition, the leaching concentration of heavy metals from the leaching test for the environmental hazard assessment showed lower than the regulated criteria.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.95-103
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• 2015

In this study, the causes and countermeasures for the leakage of a sea dyke under construction are analyzed. In general, the seabed ground is clearly divided from the embankment but a lot of parts show abnormal zones with low resistivity from the results of electric resistivity survey. Hence the causes of the leakage are considered as following: three-dimensional shear strain behavior, irregular compulsory replacement of the soft seabed ground with low strength and quality deterioration of the waterproof sheets during the closing process. The improvement method is determined by considering the constructability in the seawater and its velocity condition, durability, economic feasibility, similar application cases and so on. Consequently, a combination of low slump mortar and slurry grouting and injection method is selected as an optimum combination. Mixing ratio and improvement pattern are determined after drilling investigation and pilot test. The improvement boundary is separated into general and intense leakage area. The construction is performed with each pattern and the improvement effects are confirmed. The confirmed effects with various tests after completion show tolerable ranges for all of the established standards. Finally, various issues such as prediction of length of the waterproof sheet, installation of it against seawater velocity, etc. should be considered when sea dykes are designed or executed around the western sea which has high tide difference.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.403-410
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• 2017

We collected fishes at the 12,873 sites in stream order (1~7) from 2008 to 2016. In the results, two populations(Zacco platypus and Zacco koreanus) represented distributional differences in the stream order gradient, and correlation analysis showed that the two populations had a potential competitive relationship. The ecological characteristics of the fish except for the Z. platypus and the Z. koreanus, according to the gradient of stream order showed a pronounced gradient in the species such as intermediate species, sensitive species, carnivores, herbivores and omnivores. The two populations showed a high correlation between intermediate species, sensitive species of the tolerance guild and omnivores, insectivores of the trophic guild. Fish assessment index (FAI) was negative relation with stream order. According to the stream order gradient, the two populations showed different correlations with FAI.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.109-114
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• 2011

The objective of this study was to investigate the effects of environments (farms born, testing groups, age at the tests, date at slaughter, ages at slaughter) on body weights at 6, 12, 18 and 24 months of ages, body type measurements at 18 months of age and carcass characteristics in Hanwoo steer populations that were collected from commercial farms and reared in a progeny testing station. Performances of a total of 1,838 steer calves set for tests from 2004 to 2008 were recorded. Carcass characteristics were the carcass grading results evaluated and data collected slaughter scores at 24 months of age. For growth traits of all age classes and body type traits measured at 18 months of age, farms born, test group and linear covariate of age at test were fit in the models. For carcass traits, date at slaughter and linear covariate of ages at slaughter were fit in the models. Effect of farm at birth was not significant for body weight at 24 months of age. Carcass weight, eye muscle area, yield score and back fat thickness were affected by dates at slaughter but not by the ages at slaughter. Marbling score, however, was affected by these two effects. Farms at birth did not seem to affect body type measures greatly. This study will be utilized for Hanwoo Steers genetic evaluation.

• The KIPS Transactions:PartB
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• v.13B no.2 s.105
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• pp.83-88
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• 2006

Digital image processing algorithm was proposed to measure the area inside of an object image using angle-distance graph used to analyze the pattern of an object in the digital image processing techniques. The first angle-distance graph is generated from a point inside of an object area. The second angle-distance graphs are generated for the areas missed in the first graph by extracting the positions with large gradient in the first angle-distance graph. The order of the graph increases according to the complexity of an object pattern. Size of the area inside of an object boundary is measured by integrating square of distance multiplied by angle for each area from the hierarchical angie-distance graphs.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.357-360
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• 1998

4층구조인 다층퍼셉트론으로부터 입력층을 제외한 각 측의 출력성분을 하위은닉층으로 귀환하는 3모델의 다층회귀신경망을 구성하고, 각 모델별 망의 크기에 따른 음성인식성능을 분석 비교한다. 과거의 입력신호를 출력층에서 예측하여 오차신호를 계산하고, 이 오차신호가 최소화하는 방향으로 연결세기를 조정한다. 실험결과 3회귀모델중 상위은닉층의 회귀연결방식이 가장 양호한 인식율을 나타내었으며, 각 망 공히 상, 히위은닉층의 뉴런수 10, 15개, 예측차수 3, 4차 일 때 인식성능이 양호하였다. 그리고 회귀신경망이 비회귀신경망에 비해 인식율이 크게 향상된다는 것을 확인 할 수 있었다.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.53-62
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• 2011

During the construction of vertical cutoff walls, filtration of bentonite slurry into the adjacent soil formation fabricates a layer of bentonite filter cake on the wall surface. The bentonite filter cake possesses much lower hydraulic conductivity compared to that of backfill materials in the cutoff wall. Hydraulic conductivity of bentonite filter cakes formed with three different types of bentonites has been measured by performing the modified fluid loss test under various pressure levels. Three different mixture ratios, 4, 6, and 8%, were selected for fabricating bentonite filter cakes to represent common field conditions. Two analysis methods for interpreting the experimental data from the modified fluid loss tests were employed to estimate hydraulic conductivity of the bentonite cakes. The range of hydraulic conductivities of the three bentonite cakes is between $2.15{\times}10^{-11}\;m/s$ and $2.88{\times}10^{-10}\;m/s$ which is 1 to 2.7 orders of magnitude lower than that of the design cutoff wall backfill. The stress distribution and thickness of the bentonite cakes were also evaluated in this paper.