• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.299-307
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• 2022

Harmony Search (HS) is a relatively recently developed meta-heuristic optimization algorithm, and various studies have been conducted on it. HS is based on the musician's improvisational performance, and the objective variables play the role of the instrument. However, each instrument is given only a sound range, and there is no concept of a scale that can be said to be the basis of music. In this study, the performance of the algorithm is improved by introducing a scale to the existing HS and quantizing the bandwidth. The introduced scale was applied to HM initialization instead of the existing method that was randomly initialized in the sound band. The quantization step can be set arbitrarily, and through this, a relatively large bandwidth is used at the beginning of the algorithm to improve the exploration of the algorithm, and a small bandwidth is used to improve the exploitation in the second half. Through the introduction of scale and bandwidth quantization, it was possible to reduce the algorithm performance deviation due to the initial value and improve the algorithm convergence speed and success rate compared to the existing HS. The results of this study were confirmed by comparing examples of optimization values for various functions with the conventional method. Specific comparative values were described in the simulation.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.37-46
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• 2008

Application of resilient modulus, representing mechanical behavior of pavement materials, has become general concept for pavement design, analysis and maintenance after '86 AASHTO selected it as a basic input property of subgrade. It is known that resilient modulus of domestic subgrade soil is affected greatly by material factors, such as water content and dry weight unit, and stress components, such as deviatoric stress and confining stress, while effects of loading frequency and loading repeat were regarded negligible. If design based on resilient modulus is to be successfully implemented, design input variables of relevant models should be able to reflect local conditions. In this study, generalized mechanical model for subgrade is proposed. Model parameters are estimated from test results. Verification of the model was performed through finite element analysis using the proposed model, which showed good agreement with measured results of pavement deflections.

• Journal of the Korean Geotechnical Society
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• v.39 no.6
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• pp.13-19
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• 2023

Lunar ice is a resource available for future human exploration in deep space and long-term extraterrestrial habitat. However, the origin and nature of lunar ice remains unclear. In addition to remote sensing, international space agencies are competitively planning and conducting missions for lunar surface exploration to determine the existence and resource extent of lunar ice. If a sufficient amount of lunar ice is confirmed, its future in-situ resource utilization is expected to be greatly beneficial. However, due to ice extraction, settlement may occur, which should be taken into account from a geotechnical engineering perspective. Herein, experimental investigations of the potential settlement caused by lunar ice extraction were conducted and different textures of lunar ice were simulated. Consequently, it was confirmed that significant settlement occurs even at the initial water content of ~10% in lunar regolith simulant-ice-mixed soil.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.322-322
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• 2022

유역 모형은 강우가 유출에 이르는 과정을 수문학적으로 재현해낼 수 있는 도구이다. 초기의 모형은 간단한 수준에서 유출과정을 모의하는데 그쳤으나, 기술이 발전함에 따라 유역 모형에 적용되는 매개변수의 수가 점차 늘어나게 되며 이론적 신뢰성과 복잡성을 동시에 갖게 되었다. 유역 모형은 집중형 모형과 분포형 모형으로 대별할 수 있는데, 기존에는 저류 함수법을 근간으로 하는 개념 기반의 HEC-HMS HEC-RAS 등과 같은 집중형 모형을 널리 사용한 반면, 점차 격자 기반에서 물리적 계산을 통해 유출 과정을 모의할 수 있는 GSSHA, Vflo, SWAT과 같은 분포형 모형의 활용이 늘어나고 있는 추세이다. 집중형 모형은 관측자료를 통해 산정된 경험식에 의존하고 있는 반면, 분포형 모형의 경우 각 격자가 가지고 있는 시·공간적 매개변수를 통해 물리적으로 유출과정을 계산하여 신뢰성을 확보하기에 유리하며, 미계측 유역에서도 활용이 가능하다. 지하수는 유역 모형의 댜양한 매개변수들 중 지표면 유출량에 밀접한 영향을 미치는 인자이다. 그럼에도 아직까지 경험식에 의존한 집중형 모형이 주를 이루고 있는 국내에서는 분포형 모형에 적용가능한 매개변수 최적화에 대한 연구는 미진한 실정이다. 이에 본 연구에서는 분포형 유역 모형의 침투모의 과정에 관여하는 공간 매개변수 중 밀접한 연관을 띠고 있는 대수층 깊이에 대하여 분석하였다. 여러 공간매개변수 중 침투능과 관계가 깊은 대수층 깊이에 대해 가장 적합한 매개변수 값을 도출해 내는 것이 본 연구의 최종 목적이라고 할 수 있으며, 분석은 국내 자연하천 유역을 대상으로 분포형 유역 모형에 일반적인 수준으로 적용할수 있는 범위를 검토하였다. 본 연구를 통하여 분포형 유역 모형에서 하나의 매개변수인 대수층 깊이의 정량화에 기여되기를 바란다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.463-463
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• 2022

도시하천은 급속한 경제성장과 개발 등 여건변화에 따라 크게 변화되어왔다. 이에 하천은 본연의 모습과 가치를 잃고 인공적인 모습으로 변해 하천의 주요 기능인 자정작용, 생태계 건강성 유지 등의 기능을 잃고 도시 활동에 따른 오염물질에 노출되어가고 있는 실정이다. 이로 인한 부정적인 영향으로 도시민의 삶의 질과 만족도 또한 하락되고 있다. 본 연구에서는 부산의 대표하천인 수영강을 대상으로 도시하천 수질 개선을 위한 도시민의 지불의사를 추정하였다. 비시장가치를 추정하기 위해 조건부가치측정법(CVM, Contingent Valuation Method)을 적용하여 수질개선에 따른 지불의사(WTP, Willingness To Pay)를 파악하고 경제적 가치를 추정하였다. 가상시나리오는 EPA, water quality ladder의 개념을 이용하여 현재 수영강 수질이 오염된 물(4등급)이라고 가상시장을 설정하고 낚시가 가능한 수준(2등급)까지 개선을 시키고자 할 때의 지불의사를 물었다. 이때 지불수단은 기부금의 형태로 연 1회 향후 5년간 지불기간을 설정하였다. WTP 모형추정은 KDI에서 제시하고 있는 로지스틱분포 함수와 스파이크 모형을 사용하여 WTP를 추정하였다. 스파이크 모형의 추정결과 평균 지불의사액은 12,255원으로 부산광역시 전체 가구 수인 1,392,291가구(2019년)에 적용할 경우 향후 5년간 연 170억 원의 재원을 확보할 수 있는 것으로 나타났다. 지불의사 추정결과 수영강 인접 지역주민의 지불의사가 높게 추정되었고, 부산시민이 수영강을 자연과 생태보전 기능하천으로 인지하고 있음(56.5%)을 고려 할 때, 하천환경개선을 통한 지불의사의 상승은 도시하천 가치 향상이 될 수 있을 것으로 판단된다. 또한 도시민의 기대수준 충족과 더불어 도시하천 가치상승을 위한 부족한 재원까지도 조달 할 수 있는 방안의 기초를 마련 할 수 있을 것이라 판단된다.

• Communications of Mathematical Education
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• v.37 no.4
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• pp.653-674
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• 2023

The development of mathematical problem solving ability and the making(transforming) mathematical problems are consistently emphasized in the mathematics curriculum. However, research on the problem making methods or the analysis of the characteristics of problem making methods itself is not yet active in mathematics education in Korea. In this study, we concretize the method of deductive problem making(DPM) in a different direction from the what-if-not method proposed by Brown & Walter, and present the characteristics and phases of this method. Since in DPM the components of the problem solving process of the initial problem are changed and problems are made by going backwards from the phases of problem solving procedure, so the problem solving process precedes the formulating problem. The DPM is related to the verifying and expanding the results of problem solving in the reflection phase of problem solving. And when a teacher wants to transform or expand an initial problem for practice problems or tests, etc., DPM can be used.

• Environmental and Resource Economics Review
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• v.23 no.4
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• pp.719-746
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• 2014

This study attempts to estimate the value of the water quality improvement by deriving the equilibrium price of the water pollutant emission permit for the imaginary water pollutant emission trading market. It is reasonable to say that there is already an implicit social agreement for the unit value of water pollutant, when the government set the Total Water Pollutant Loading System for the major river basin as a part of the Comprehensive Measures for Water Management, particularly for the Nakdong River Basin. Therefore, we can derive the unit value of water pollutant emission, which is already implied in the pollution allowance for each city or county by the Total Water Pollutant Loading System. Once estimated, it will be useful to the economic assessment of the water quality related projects. An imaginary water pollutant emission trading system for the Nakdong River Basin, where Total Water Pollutant Loading System is already effective, is constructed for the estimation of the equilibrium price of water pollutant permit. By estimating marginal abatement cost curve or each city or county, we can compute the equilibrium price of the permit and then it is regarded as the economic value of the water pollutant. The marginal net benefit function results from the relationship between the emission and the benefit, and then the equilibrium price of permit comes from constructing the excess demand function of the permit by using the total allowable permit of the local government entity. The equilibrium price of the permit would be estimated to be $1,409.3won/kg{\cdot}BOD$. This is within reasonable boundary compared for the permit price compared to foreign example. This permit price would be applied to calculate for the economic value of the water quality pollutants, and also be expected to use directly for the B/C analysis of the business involved with water quality change.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.227-240
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• 2011

New concepts and ideas often result from extensive recombination of existing concepts or ideas. Both researchers and developers build on existing concepts and ideas in published papers or registered patents to develop new theories and technologies that in turn serve as a basis for further development. As the importance of patent increases, so does that of patent analysis. Patent analysis is largely divided into network-based and keyword-based analyses. The former lacks its ability to analyze information technology in details while the letter is unable to identify the relationship between such technologies. In order to overcome the limitations of network-based and keyword-based analyses, this study, which blends those two methods, suggests the keyword network based analysis methodology. In this study, we collected significant technology information in each patent that is related to Light Emitting Diode (LED) through text mining, built a keyword network, and then executed a community network analysis on the collected data. The results of analysis are as the following. First, the patent keyword network indicated very low density and exceptionally high clustering coefficient. Technically, density is obtained by dividing the number of ties in a network by the number of all possible ties. The value ranges between 0 and 1, with higher values indicating denser networks and lower values indicating sparser networks. In real-world networks, the density varies depending on the size of a network; increasing the size of a network generally leads to a decrease in the density. The clustering coefficient is a network-level measure that illustrates the tendency of nodes to cluster in densely interconnected modules. This measure is to show the small-world property in which a network can be highly clustered even though it has a small average distance between nodes in spite of the large number of nodes. Therefore, high density in patent keyword network means that nodes in the patent keyword network are connected sporadically, and high clustering coefficient shows that nodes in the network are closely connected one another. Second, the cumulative degree distribution of the patent keyword network, as any other knowledge network like citation network or collaboration network, followed a clear power-law distribution. A well-known mechanism of this pattern is the preferential attachment mechanism, whereby a node with more links is likely to attain further new links in the evolution of the corresponding network. Unlike general normal distributions, the power-law distribution does not have a representative scale. This means that one cannot pick a representative or an average because there is always a considerable probability of finding much larger values. Networks with power-law distributions are therefore often referred to as scale-free networks. The presence of heavy-tailed scale-free distribution represents the fundamental signature of an emergent collective behavior of the actors who contribute to forming the network. In our context, the more frequently a patent keyword is used, the more often it is selected by researchers and is associated with other keywords or concepts to constitute and convey new patents or technologies. The evidence of power-law distribution implies that the preferential attachment mechanism suggests the origin of heavy-tailed distributions in a wide range of growing patent keyword network. Third, we found that among keywords that flew into a particular field, the vast majority of keywords with new links join existing keywords in the associated community in forming the concept of a new patent. This finding resulted in the same outcomes for both the short-term period (4-year) and long-term period (10-year) analyses. Furthermore, using the keyword combination information that was derived from the methodology suggested by our study enables one to forecast which concepts combine to form a new patent dimension and refer to those concepts when developing a new patent.

• Geotechnical Engineering
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• v.12 no.3
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• pp.127-148
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• 1996

Recently, foundations of heavy structures such as bridge abutments have been built on slopes or near the crest of slopes at an increasing rate. Because the bearing capacity of such foundations is considerably lower than the bearing capacity of the same soil on a level ground, deep footings such as piles and caissons are often used. However, the costs of such methods are generally very high. One of the new techniques to overcome the problem is to place reinforcing members such as geosynthetics or metal strips horizontally at some depths beneath the footings. Rational methods of analysis to predict the bearing capacity of footings in reinforced slopes are therefore needed. This paper proposes an analytical method for estimating the increase in bearing capacity gained from the included horizontal strips or ties of tensile reinforcing in the foundation soil below the footing built near the crest of a slope. A failure mechanism, including the concept of'wide slab effect', adopted in the present study for analyzing the bearing capacity of foundations in reinforced slopes, is established through the observed model test behaviors described by Binquet SE Lee and Huang et al, and the Boussinesq solutions. The analytical results are then compared with the experimental data described in the paper by Huang et al. Also in order to properly evaluate the soil reinforcement interaction, typical pullout test values of the apparent friction coefficient, which usually vary with depths owing to both the increase of the shearing volume and the increase in local stress caused by soil dilatancy, are analyzed and related functionally. Furthermore, analytical parametric studies are carried out to investigate the effect and significance of various pertinent parameters associated with design of reinforced slope foundations. Keywords : Bearing capacity, Reinforced slope, Slab effect, Friction coefficient.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.57-63
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• 2004

Primary productivity of phytoplankton was measured by $^{14}C$ method from January to October of 1996 in Seonakdong River. This river was a highly productive freshwater showing the euphotic depth of 1.4 m in August and 2.1 m in the remaining season. Chlorophyll-a concentrations of phytoplankton ranged from 67 ${\mu}g\;L^{-1}$ to 894 ${\mu}g\;L^{-1}$ and showed the great increase in August. Maximum specific productivity was 2.1 ${\sim}$4.3 mg C mg $chl-a{-1}\;hr^{-1}$ and occurred above 0.4m depth. In photosynthesis-irradiance relation, photoinhibition or photosynthetic suppression of phytoplankton occurred clearly in the cold seasons, while phytoplankton (mainly Microcystis aeruginosa and its relatives) in August did not show any symptom of the photosynthetic inhibition against the high irradiance. The specific productivity of phytoplankton was eventually dependant upon incident irradiance to show the linear correlation with received irradiance infield, and the areal productivity of phytoplankton upon chlorophyll-a standing crops. In the downstream of the Nakdong River, phytoplankton productions have linearly increased since the estuarine barrage construction to reflect the gradual eutrophication in the estuarine area. Average chlorophyll-a increase of 10 ${\mu}g\;chl-a\;L{-1}$ absolutely corresponded to the primary production acceleration of 30 mg C $m^{-2}\;day^{-1}$ on the annual basis.