• Korean Journal of Logic
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• v.22 no.3
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• pp.397-415
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• 2019

This paper deals with the pretabular property of some fuzzy logics. For this, we first introduce the involutive idempotent uninorm logics IdIUL and IUML and examine the relationship between IdIUL and the another well-known system $RM^T$. Next, we show that IUML is pretabular, whereas IdIUL is not.

• Korean Journal of Logic
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• v.6 no.2
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• pp.83-106
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• 2003

선호구조의 논리를 결정모델에 적용시킬 때 선호구조는 일반적으로 특정 수치적 순서화 조건을 만족하게끔 표현된다. 그래야 주어진 선택지들을 둘러싼 개인 혹은 집단의 선호구조에 관한 정보가 형식적으로 표출될 수 있다고 여겨져 왔다. 그러나 선호구조의 수치적 순서화에 의해서만 선호관계의 정보가 형식적으로 표출될 수 있다는 성각은 일종의 독단이다. 더욱이 다양한 선택지의 결합에 의한 선호구조의 정보 이동은 기존의 수치적 순서화 속에서 제대로 다루어질 수 없다. 하나의 대안으로서 선형대수의 그래프이론에 바탕을 둔 선호구조의 질적 순서화 방식을 제안한다. 개인 혹은 집단의 선호구조에 관한 정보는 제안될 질적 순서화에 의해 보다 포괄적으로 다루어질 수 있다.

• Journal of Korean Society of Transportation
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• v.16 no.1
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• pp.35-46
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• 1998

본 연구의 목적은 직장인과 비직장인들의 일일교통발생량과 관련된 시간적 요인들과 인구 및 사회.경제적 변수들의 관계를 비교.분석하는 것이다. 이러한 분석은 도심내 직장인과 비직장인들의 교통발생특성뿐만 아니라 교통방생행위 예측을 위한 기초적 이해를 제공한다. 본 연구의 대상 직장인과 비직장인들의 교통발생행태는 미국 텍사스주 샌 안토니오시에 살고 있는 사람들로 한정하였다. 본 연구에서 관련자료의 비교.분석한 결과 첫째, 직장인들의 평균 일일교통발생량이 비직장인들 보다 많다. 주활동 이전의 직장인의 교통발생량은 비직장인들보다 적고, 주활동 이후에는 직장인들이 비직장인들보다 많은 교통을 발생시키고 있다. 특히, 오후 교통혼잡시간대 직장인들의 교통발생이 비직장 인들보다 많은 차이를 나타낸다. 둘째, 두 집단의 주활동 기간은 그 밖의 다른 활동에 소비한 시간과 주활동 전후의 교통발생수와 반비례 상관관계를 갖는다. 주활동의 시간의 다소에 따라 다른활동을 위한 시간적 여유와 교통량과 밀접한 관계 때문에 주활동의 시간은 교통량분석에 있어 결정적 변수이다. 마지막으로 출근하기 이전 직장인들의 교통량은 사회.경제적 변수들과 관계없이 독립적으로 발생되나, 퇴근한 이후에는 모든 인구 및 사회.경제적 변수들과 밀접한 함수관계를 갖는다. 비직장인들의 교통발생은 자동차 보유대수와 경제적 여유수준과 밀접한 관계를 나타낸다.

• Economic and Environmental Geology
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• v.43 no.4
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• pp.359-369
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• 2010

This study characterizes aquifer system and hydrogeologic property in the western half of Jeju Island where wells were drilled for regional water supply in three sub-areas (northwestern, western, and southwestern sub-areas). The aquifer system of the northwestern sub-area is largely composed of upper high-permeability layer, upper low-permeability layer, lower high-permeability layer, and lower low-permeability layer. On the other hand, the aquifer systems of the western and southwestern sub-areas are mostly composed of upper low-permeability layer, high-permeability layer, and lower low-permeability layer. Transmissivity and specific capacity decrease in the order of the northwestern, western, and southwestern sub-areas. The relationship between specific capacity and the top surface of tuff is negative with a high correlation coefficient of -0.848, indicating that the tuff acts as the bottom of the aquifer. Groundwater level change due to the 2004 Sumatra earthquake is an average of 23.74 cm in the northwestern sub-area, an average of 9.48 cm in the western sub-area, and none in the southwestern sub-area. Further, it is found that groundwater change due to the earthquake has a positive relationship with transmissivity and specific capacity.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.269-284
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• 2006

Aquifer responses to the river stage fluctuations were analyzed between the groundwater level and the river stage in an alluvial aquifer. The auto-correlation and cross-correlation as a time series analysis were applied. Study site is a floodplain in the Mangyeong river. Groundwater levels in each depth representing the silt and sand(SS), gravel and sand(GS), and weathered zone(WZ) layer were monitored. The groundwater levels were more sensitive to the river stage fluctuations than rainfall. Since the river stages are influenced by the gate operations downstream and tide, show periodic patterns, and the correlation coefficients with rainfall is low. Cross-correlation function between groundwater level in each depth do not show any delay time, then response time is very short to each depth. Cross-correlation analysis were performed to estimate the response time of groundwater levels to river stage fluctuations. Groundwater levels respond to the river stage within 30 minutes to 1 hour in wells near the stream. Short time lag between groundwater level and river stage indicates the quick response. A different response time imply the hydraulic inhomogeneity of the site, and a probable high permeability zone between river and aquifer can be inferred. Mangyeong-river in study site is a gaining stream normally, and river stage rising by gate operation or floods makes river water flow into groundwater. The auto-correlation and cross-correlation functions as a time series analysis can be a good tool to interpret the aquifer responses to stream stage fluctuation

• Journal of KIISE:Databases
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• v.29 no.5
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• pp.347-357
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• 2002

Graphs have provided a powerful methodology to solve a lot of real-world problems, and therefore there have been many proposals on the graph representations and algorithms. But, because most of them considered only memory-based graphs, there are still difficulties to apply them to large-scale problems. To cope with the difficulties, this paper proposes a graph representation and graph algorithms based on the well-developed relational database theory. Graphs are represented in the form of relations which can be visualized as relational tables. Each vertex and edge of a graph is represented as a tuple in the tables. Graph algorithms are also defined in terms of relational algebraic operations such as projection, selection, and join. They can be implemented with the database language such as SQL. We also developed a library of basic graph operations for the management of graphs and the development of graph applications. This database approach provides an efficient methodology to deal with very large- scale graphs, and the graph library supports the development of graph applications. Furthermore, it has many advantages such as the concurrent graph sharing among users by virtue of the capability of database.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.79-90
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• 2004

In this study, we applied the Bayesian Networks for the case of the trip generation models using the Seoul metropolitan area's house trip survey Data. The household income was used for the independent variable for the explanation of household size and the number of cars in a household, and the relationships between the trip generation and the households' social characteristics were identified by the Bayesian Networks. Furthermore, trip generation's characteristics such as the household income, household size and the number of cars in a household were also used for explanatory variables and the trip generation model was developed. It was found that the Bayesian Networks were useful tool to overcome the problems which were in the traditional trip generation models. In particular the various transport policies could be evaluated in the very short time by the established relationships. It is expected that the Bayesian Networks will be utilized as the important tools for the analysis of trip patterns.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.554-570
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• 1990

he rolling contact behaviors between a smooth ball and a flat rough surface under dynamic load are intricately affected by many factors, such as the diameter of a ball, normal load and the roughness of a flat surface etc. Accordingly, the experimental study is done to find them on the base of elastic hysteresis loss as theoretical approach is very difficult. The experimental apparatus composed of damped-free vibration system is used. This paper investigates the damping characteristics on the rolling contact area through rolling friction force and logarithmic decrement versus displacement obtained in accordance with the variations of those factors, and presents a new experimental method to find out contact width using the relations of logarithmic decrement and rolling friction force with displacement.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.406-409
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• 2004

최근 Lee et al.$^{l-2)}$ 은 화강암질 편마암내 균열면의 방해석이 Eu의 변화에 큰 영향을 주며, 아울러 Eu 은 Am의 유사체로서 매우 적합한 원소라고 제안하였다. 이 논문에서는 1)희토류원소와 액티나이드 원소의 이온반경, 배위수 등의 상호비교와 2) 응집력(cohesive energy)의 유사성과 물리적/화학적 특성 그리고 3) 희토류원소 지구화학의 최근 연구결과를 토대로 하여, 고준위 방사성 핵종원소인 Am의 지질매체내 거동을 예측하기 위한 유사체(analog)로서 Eu이 매우 유용한 역할을 해준다는 가설2)을 검증한 결과를 보고하고자 한다. 연구방법으로서, 핵종원소의 지질매체별 흡착특성을 밝혀내기 위해 금번 실험에서는 희토류원소 암상별 분포의 특성을 고려하여 4종류(화강암질 편마암류 2종, meta-basalts, 응회암)의 시료를 선별하였다. 방사화학적 흡탈착 실험의 핵종동위원소로서는 152Eu와 241Am을 선택하였다. 이는 본 연구팀의 연구결과, Eu과 Am의 밀접한 물리적/화학적 상관관계 그리고 지질환경내에서의 거동특성을 고려한 것이다. 실험결과 양 동위원소의 지질매체와의 흡착 반응 특성을 비교해 볼 때, 시간의 경과에 따라 서로간에 매우 유사한 양상의 증감을 보여주면서 변화함을 알 수가 있었다. 이 결과는 희토류원소가 액티나이드 원소의 지질환경내 거동예측을 위한 유사체로서 매우 훌륭한 도구라는 것을 입증해 주는 것이라 할 수 있다.

• International Journal of Highway Engineering
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• v.2 no.1
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• pp.147-156
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• 2000

Compaction is known to critically affect pavement performance. Due to its importance, a theoretical modelling of compacted density in the term of number of roller coverages is attempted by assuming compaction process essentially identical to pavement rutting. Excellent data fittings by the developed equation may prove the validation of assumptions made as well as justification of its use. According to the derived equation, a plot of density difference with respect to number of roller coverages in the logarithmic scale Produces a linear relationship. However, this linearity is turned out to be deviated by cooling effect, change of amplitude and frequency. Investigation of these three factors proposes a new generalized compaction density equation, which shows a promising future. By applying this general formula, the equations for the number of roller coverages required and the final compaction density obtained for a particular compaction project is derived first time in compaction research.